linux-omap.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage
@ 2020-10-19 10:06 Thomas Gleixner
  2020-10-19 10:06 ` [patch V2 01/13] USB: sisusbvga: Make console support depend on BROKEN Thomas Gleixner
                   ` (12 more replies)
  0 siblings, 13 replies; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Thomas Winischhofer, Greg Kroah-Hartman,
	linux-usb, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Johan Hovold, Mathias Nyman, Valentina Manea, Shuah Khan,
	Alan Stern, linux-omap, Kukjin Kim, Krzysztof Kozlowski,
	linux-arm-kernel, linux-samsung-soc, Felipe Balbi, Duncan Sands

Folks,

in the discussion about preempt count consistency accross kernel configurations:

  https://lore.kernel.org/r/20200914204209.256266093@linutronix.de/

Linus clearly requested that code in drivers and libraries which changes
behaviour based on execution context should either be split up so that
e.g. task context invocations and BH invocations have different interfaces
or if that's not possible the context information has to be provided by the
caller which knows in which context it is executing.

This includes conditional locking, allocation mode (GFP_*) decisions and
avoidance of code paths which might sleep.

In the long run, usage of 'preemptible, in_*irq etc.' should be banned from
driver code completely.

The usage of such constructs in USB is rather limited. Most of it is in
debug code and (misleading) comments. But of course there are also a few
few bugs including one unfixable.

That's an update to V1 of this series which can be found here:

  https://lore.kernel.org/r/20201014145215.518912759@linutronix.de

Changes vs. V1:

 - Fix the keyspan_pda query buffer properly

 - Seperate the static change from the comments changes

 - Address review feedback vs. comments

 - Fix the typo in isp1362

 - Collected acks/reviewed-by tags

Thanks,

	tglx


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 01/13] USB: sisusbvga: Make console support depend on BROKEN
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-19 10:06 ` [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage Thomas Gleixner
                   ` (11 subsequent siblings)
  12 siblings, 0 replies; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Thomas Winischhofer, Greg Kroah-Hartman,
	linux-usb, stable, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Johan Hovold, Mathias Nyman, Valentina Manea, Shuah Khan,
	Alan Stern, linux-omap, Kukjin Kim, Krzysztof Kozlowski,
	linux-arm-kernel, linux-samsung-soc, Felipe Balbi, Duncan Sands

The console part of sisusbvga is broken vs. printk(). It uses in_atomic()
to detect contexts in which it cannot sleep despite the big fat comment in
preempt.h which says: Do not use in_atomic() in driver code.

in_atomic() does not work on kernels with CONFIG_PREEMPT_COUNT=n which
means that spin/rw_lock held regions are not detected by it.

There is no way to make this work by handing context information through to
the driver and this only can be solved once the core printk infrastructure
supports sleepable console drivers.

Make it depend on BROKEN for now.

Fixes: 1bbb4f2035d9 ("[PATCH] USB: sisusb[vga] update")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Winischhofer <thomas@winischhofer.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Cc: stable@vger.kernel.org
---
 drivers/usb/misc/sisusbvga/Kconfig |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/misc/sisusbvga/Kconfig
+++ b/drivers/usb/misc/sisusbvga/Kconfig
@@ -16,7 +16,7 @@ config USB_SISUSBVGA
 
 config USB_SISUSBVGA_CON
 	bool "Text console and mode switching support" if USB_SISUSBVGA
-	depends on VT
+	depends on VT && BROKEN
 	select FONT_8x16
 	help
 	  Say Y here if you want a VGA text console via the USB dongle or


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
  2020-10-19 10:06 ` [patch V2 01/13] USB: sisusbvga: Make console support depend on BROKEN Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-25 16:56   ` Johan Hovold
  2020-10-19 10:06 ` [patch V2 03/13] USB: serial: keyspan_pda: Consolidate room query Thomas Gleixner
                   ` (10 subsequent siblings)
  12 siblings, 1 reply; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Johan Hovold, Greg Kroah-Hartman, linux-usb, Thomas Winischhofer,
	Mathias Nyman, Valentina Manea, Shuah Khan, Alan Stern,
	linux-omap, Kukjin Kim, Krzysztof Kozlowski, linux-arm-kernel,
	linux-samsung-soc, Felipe Balbi, Duncan Sands

keyspan_pda_write() uses in_interrupt() to check whether it is safe to
invoke functions which might sleep.

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be seperated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

Aside of that it does not cover all contexts which cannot sleep,
e.g. preempt disabled regions which cannot be reliably detected on all
kernel configurations.

With the current printk() implementation console->write() can be invoked
from almost any context. The upcoming rework of the console core will
provide thread context for console drivers which require to sleep.

For now, restrict the room query which can sleep to tty writes which happen
from preemptible task context.

The usability for dmesg output is limited anyway because it's almost
guaranteed to drop the 'LF' which is submitted after the dmesg line because
the device supports only one transfer on flight. Same for any printk()
which is coming in before the previous transfer has been done.

This new restriction does not make it worse than before, but it makes the
condition correct under all circumstances.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Johan Hovold <johan@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org

---
 drivers/usb/serial/keyspan_pda.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -477,10 +477,12 @@ static int keyspan_pda_write(struct tty_
 
 	count = (count > port->bulk_out_size) ? port->bulk_out_size : count;
 
-	/* Check if we might overrun the Tx buffer.   If so, ask the
-	   device how much room it really has.  This is done only on
-	   scheduler time, since usb_control_msg() sleeps. */
-	if (count > priv->tx_room && !in_interrupt()) {
+	/*
+	 * Check if we might overrun the Tx buffer. If so, ask the device
+	 * how much room it really has. This can only be invoked for tty
+	 * usage because the console write can't sleep.
+	 */
+	if (count > priv->tx_room && tty) {
 		u8 *room;
 
 		room = kmalloc(1, GFP_KERNEL);


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 03/13] USB: serial: keyspan_pda: Consolidate room query
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
  2020-10-19 10:06 ` [patch V2 01/13] USB: sisusbvga: Make console support depend on BROKEN Thomas Gleixner
  2020-10-19 10:06 ` [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-25 17:05   ` Johan Hovold
  2020-10-19 10:06 ` [patch V2 04/13] USB: serial: digi_acceleport: Remove in_interrupt() usage Thomas Gleixner
                   ` (9 subsequent siblings)
  12 siblings, 1 reply; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Sebastian Andrzej Siewior, Johan Hovold,
	Greg Kroah-Hartman, linux-usb, Thomas Winischhofer,
	Ahmed S. Darwish, Mathias Nyman, Valentina Manea, Shuah Khan,
	Alan Stern, linux-omap, Kukjin Kim, Krzysztof Kozlowski,
	linux-arm-kernel, linux-samsung-soc, Felipe Balbi, Duncan Sands

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Having two copies of the same code doesn't make the code more readable and
allocating a buffer of 1 byte for a synchronous operation is a pointless
exercise.

Allocate a byte buffer at init which can be used instead. The buffer is
only used in open() and tty->write(). Console writes are not calling into
the query. open() obviously happens before write() and the writes are
serialized by bit 0 of port->write_urbs_free which protects also the
transaction itself.

Move the actual query into a helper function and cleanup the usage sites in
keyspan_pda_write() and keyspan_pda_open().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Johan Hovold <johan@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
---
V2; Allocate a real buffer (Alan)
---
 drivers/usb/serial/keyspan_pda.c |  108 +++++++++++++++++----------------------
 1 file changed, 49 insertions(+), 59 deletions(-)

--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -47,6 +47,7 @@ struct keyspan_pda_private {
 	struct work_struct			unthrottle_work;
 	struct usb_serial	*serial;
 	struct usb_serial_port	*port;
+	u8			*query_buf;
 };
 
 
@@ -436,6 +437,31 @@ static int keyspan_pda_tiocmset(struct t
 	return rc;
 }
 
+/*
+ * Using priv->query_buf is safe here because this is only called for TTY
+ * operations open() and write(). write() comes post open() obviously and
+ * write() itself is serialized via bit 0 of port->write_urbs_free. Console
+ * writes are never calling into this.
+ */
+static int keyspan_pda_query_room(struct usb_serial *serial,
+				  struct keyspan_pda_private *priv)
+{
+	int res;
+
+	res = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
+			      6, /* write_room */
+			      USB_TYPE_VENDOR | USB_RECIP_INTERFACE | USB_DIR_IN,
+			      0, /* value */
+			      0, /* index */
+			      priv->query_buf,
+			      1,
+			      2000);
+	if (res != 1)
+		return res < 0 ? res : -EIO;
+
+	return (unsigned int)*priv->query_buf;
+}
+
 static int keyspan_pda_write(struct tty_struct *tty,
 	struct usb_serial_port *port, const unsigned char *buf, int count)
 {
@@ -483,39 +509,16 @@ static int keyspan_pda_write(struct tty_
 	 * usage because the console write can't sleep.
 	 */
 	if (count > priv->tx_room && tty) {
-		u8 *room;
-
-		room = kmalloc(1, GFP_KERNEL);
-		if (!room) {
-			rc = -ENOMEM;
-			goto exit;
-		}
-
-		rc = usb_control_msg(serial->dev,
-				     usb_rcvctrlpipe(serial->dev, 0),
-				     6, /* write_room */
-				     USB_TYPE_VENDOR | USB_RECIP_INTERFACE
-				     | USB_DIR_IN,
-				     0, /* value: 0 means "remaining room" */
-				     0, /* index */
-				     room,
-				     1,
-				     2000);
-		if (rc > 0) {
-			dev_dbg(&port->dev, "roomquery says %d\n", *room);
-			priv->tx_room = *room;
-		}
-		kfree(room);
+		rc = keyspan_pda_query_room(serial, priv);
 		if (rc < 0) {
-			dev_dbg(&port->dev, "roomquery failed\n");
-			goto exit;
-		}
-		if (rc == 0) {
-			dev_dbg(&port->dev, "roomquery returned 0 bytes\n");
-			rc = -EIO; /* device didn't return any data */
+			dev_dbg(&port->dev, "roomquery failed %d\n", rc);
 			goto exit;
 		}
+
+		dev_dbg(&port->dev, "roomquery says %d\n", rc);
+		priv->tx_room = rc;
 	}
+
 	if (count > priv->tx_room) {
 		/* we're about to completely fill the Tx buffer, so
 		   we'll be throttled afterwards. */
@@ -615,45 +618,26 @@ static int keyspan_pda_open(struct tty_s
 					struct usb_serial_port *port)
 {
 	struct usb_serial *serial = port->serial;
-	u8 *room;
-	int rc = 0;
 	struct keyspan_pda_private *priv;
+	int rc;
 
-	/* find out how much room is in the Tx ring */
-	room = kmalloc(1, GFP_KERNEL);
-	if (!room)
-		return -ENOMEM;
+	priv = usb_get_serial_port_data(port);
 
-	rc = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
-			     6, /* write_room */
-			     USB_TYPE_VENDOR | USB_RECIP_INTERFACE
-			     | USB_DIR_IN,
-			     0, /* value */
-			     0, /* index */
-			     room,
-			     1,
-			     2000);
+	/* find out how much room is in the Tx ring */
+	rc = keyspan_pda_query_room(serial, priv);
 	if (rc < 0) {
-		dev_dbg(&port->dev, "%s - roomquery failed\n", __func__);
-		goto error;
-	}
-	if (rc == 0) {
-		dev_dbg(&port->dev, "%s - roomquery returned 0 bytes\n", __func__);
-		rc = -EIO;
-		goto error;
+		dev_dbg(&port->dev, "roomquery failed %d\n", rc);
+		return rc;
 	}
-	priv = usb_get_serial_port_data(port);
-	priv->tx_room = *room;
-	priv->tx_throttled = *room ? 0 : 1;
+
+	priv->tx_room = rc;
+	priv->tx_throttled = rc ? 0 : 1;
 
 	/*Start reading from the device*/
 	rc = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
-	if (rc) {
+	if (rc)
 		dev_dbg(&port->dev, "%s - usb_submit_urb(read int) failed\n", __func__);
-		goto error;
-	}
-error:
-	kfree(room);
+
 	return rc;
 }
 static void keyspan_pda_close(struct usb_serial_port *port)
@@ -715,6 +699,11 @@ static int keyspan_pda_port_probe(struct
 	priv = kmalloc(sizeof(struct keyspan_pda_private), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;
+	priv->query_buf = kmalloc(1, GFP_KERNEL);
+	if (!priv->query_buf) {
+		kfree(priv);
+		return -ENOMEM;
+	}
 
 	INIT_WORK(&priv->wakeup_work, keyspan_pda_wakeup_write);
 	INIT_WORK(&priv->unthrottle_work, keyspan_pda_request_unthrottle);
@@ -731,6 +720,7 @@ static int keyspan_pda_port_remove(struc
 	struct keyspan_pda_private *priv;
 
 	priv = usb_get_serial_port_data(port);
+	kfree(priv->query_buf);
 	kfree(priv);
 
 	return 0;


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 04/13] USB: serial: digi_acceleport: Remove in_interrupt() usage
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
                   ` (2 preceding siblings ...)
  2020-10-19 10:06 ` [patch V2 03/13] USB: serial: keyspan_pda: Consolidate room query Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-25 17:16   ` Johan Hovold
  2020-10-19 10:06 ` [patch V2 05/13] usb: xhci: Remove in_interrupt() checks Thomas Gleixner
                   ` (8 subsequent siblings)
  12 siblings, 1 reply; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Johan Hovold, Greg Kroah-Hartman, linux-usb, Thomas Winischhofer,
	Mathias Nyman, Valentina Manea, Shuah Khan, Alan Stern,
	linux-omap, Kukjin Kim, Krzysztof Kozlowski, linux-arm-kernel,
	linux-samsung-soc, Felipe Balbi, Duncan Sands

From: Ahmed S. Darwish <a.darwish@linutronix.de>

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

The debug printk() in digi_write() prints in_interrupt() as context
information. TTY writes happen always in preemptible task context and
console writes can happen from almost any context, so in_interrupt() is not
really helpful.

Aside of that issuing a printk() from a console->write() callback is not a
really brilliant idea for obvious reasons.

Remove the in_interrupt() printout and make the printk() depend on tty.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Johan Hovold <johan@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org

---
 drivers/usb/serial/digi_acceleport.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -911,9 +911,10 @@ static int digi_write(struct tty_struct
 	unsigned char *data = port->write_urb->transfer_buffer;
 	unsigned long flags = 0;
 
-	dev_dbg(&port->dev,
-		"digi_write: TOP: port=%d, count=%d, in_interrupt=%ld\n",
-		priv->dp_port_num, count, in_interrupt());
+	if (tty) {
+		dev_dbg(&port->dev, "digi_write: TOP: port=%d, count=%d\n",
+			priv->dp_port_num, count);
+	}
 
 	/* copy user data (which can sleep) before getting spin lock */
 	count = min(count, port->bulk_out_size-2);


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 05/13] usb: xhci: Remove in_interrupt() checks
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
                   ` (3 preceding siblings ...)
  2020-10-19 10:06 ` [patch V2 04/13] USB: serial: digi_acceleport: Remove in_interrupt() usage Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-19 10:06 ` [patch V2 06/13] usb: host: isp1362: Replace in_interrupt() usage Thomas Gleixner
                   ` (7 subsequent siblings)
  12 siblings, 0 replies; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Mathias Nyman, Greg Kroah-Hartman, linux-usb,
	Thomas Winischhofer, Johan Hovold, Valentina Manea, Shuah Khan,
	Alan Stern, linux-omap, Kukjin Kim, Krzysztof Kozlowski,
	linux-arm-kernel, linux-samsung-soc, Felipe Balbi, Duncan Sands

From: Ahmed S. Darwish <a.darwish@linutronix.de>

The usage of in_interrupt() in drivers is phased out for various reasons.

xhci_set_hc_event_deq() has an !in_interrupt() check which is pointless
because the function is only invoked from xhci_mem_init() which is clearly
task context as it does GFP_KERNEL allocations. Remove it.

xhci_urb_enqueue() prints a debug message if an URB is submitted after the
underlying hardware was suspended. But that warning is only issued when
in_interrupt() is true, which makes no sense. Simply return -ESHUTDOWN and
be done with it.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mathias Nyman <mathias.nyman@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
---
 drivers/usb/host/xhci-mem.c |    2 +-
 drivers/usb/host/xhci.c     |    6 ++----
 2 files changed, 3 insertions(+), 5 deletions(-)

--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -2110,7 +2110,7 @@ static void xhci_set_hc_event_deq(struct
 
 	deq = xhci_trb_virt_to_dma(xhci->event_ring->deq_seg,
 			xhci->event_ring->dequeue);
-	if (deq == 0 && !in_interrupt())
+	if (!deq)
 		xhci_warn(xhci, "WARN something wrong with SW event ring "
 				"dequeue ptr.\n");
 	/* Update HC event ring dequeue pointer */
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1473,11 +1473,9 @@ static int xhci_urb_enqueue(struct usb_h
 	ep_index = xhci_get_endpoint_index(&urb->ep->desc);
 	ep_state = &xhci->devs[slot_id]->eps[ep_index].ep_state;
 
-	if (!HCD_HW_ACCESSIBLE(hcd)) {
-		if (!in_interrupt())
-			xhci_dbg(xhci, "urb submitted during PCI suspend\n");
+	if (!HCD_HW_ACCESSIBLE(hcd))
 		return -ESHUTDOWN;
-	}
+
 	if (xhci->devs[slot_id]->flags & VDEV_PORT_ERROR) {
 		xhci_dbg(xhci, "Can't queue urb, port error, link inactive\n");
 		return -ENODEV;


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 06/13] usb: host: isp1362: Replace in_interrupt() usage
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
                   ` (4 preceding siblings ...)
  2020-10-19 10:06 ` [patch V2 05/13] usb: xhci: Remove in_interrupt() checks Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-28 11:27   ` Greg Kroah-Hartman
  2020-10-19 10:06 ` [patch V2 07/13] usbip: Remove in_interrupt() check Thomas Gleixner
                   ` (6 subsequent siblings)
  12 siblings, 1 reply; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Greg Kroah-Hartman, linux-usb, Thomas Winischhofer, Johan Hovold,
	Mathias Nyman, Valentina Manea, Shuah Khan, Alan Stern,
	linux-omap, Kukjin Kim, Krzysztof Kozlowski, linux-arm-kernel,
	linux-samsung-soc, Felipe Balbi, Duncan Sands

isp1362_show_regs() is a debugging-only function, with no call sites. It
prints the cached value of the HCuPINTENB register if in_interupt() is
true, otherwise it reads the actual register content.

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

Make the conditional based on a function argument.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
---
V2: Fix silly typo
---
 drivers/usb/host/isp1362.h |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/usb/host/isp1362.h
+++ b/drivers/usb/host/isp1362.h
@@ -793,7 +793,8 @@ static void isp1362_write_fifo(struct is
 			ISP1362_REG_NO(ISP1362_REG_##r), isp1362_read_reg16(d, r));	\
 }
 
-static void __attribute__((__unused__)) isp1362_show_regs(struct isp1362_hcd *isp1362_hcd)
+static void __attribute__((__unused__))
+isp1362_show_regs(struct isp1362_hcd *isp1362_hcd, bool cached_inten)
 {
 	isp1362_show_reg(isp1362_hcd, HCREVISION);
 	isp1362_show_reg(isp1362_hcd, HCCONTROL);
@@ -815,7 +816,7 @@ static void __attribute__((__unused__))
 	isp1362_show_reg(isp1362_hcd, HCXFERCTR);
 	isp1362_show_reg(isp1362_hcd, HCuPINT);
 
-	if (in_interrupt())
+	if (cached_inten)
 		DBG(0, "%-12s[%02x]:     %04x\n", "HCuPINTENB",
 			 ISP1362_REG_NO(ISP1362_REG_HCuPINTENB), isp1362_hcd->irqenb);
 	else


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 07/13] usbip: Remove in_interrupt() check
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
                   ` (5 preceding siblings ...)
  2020-10-19 10:06 ` [patch V2 06/13] usb: host: isp1362: Replace in_interrupt() usage Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-19 10:06 ` [patch V2 08/13] usb: hosts: Remove in_interrupt() from comments Thomas Gleixner
                   ` (5 subsequent siblings)
  12 siblings, 0 replies; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Valentina Manea, Shuah Khan, Greg Kroah-Hartman, linux-usb,
	Thomas Winischhofer, Johan Hovold, Mathias Nyman, Alan Stern,
	linux-omap, Kukjin Kim, Krzysztof Kozlowski, linux-arm-kernel,
	linux-samsung-soc, Felipe Balbi, Duncan Sands

From: Ahmed S. Darwish <a.darwish@linutronix.de>

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

usbip_recv() uses in_interrupt() to conditionally print context information
for debugging messages. The value is zero as the function is only called
from various *_rx_loop() kthread functions. Remove it.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Cc: Valentina Manea <valentina.manea.m@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org

---
 drivers/usb/usbip/usbip_common.c |    5 -----
 1 file changed, 5 deletions(-)

--- a/drivers/usb/usbip/usbip_common.c
+++ b/drivers/usb/usbip/usbip_common.c
@@ -324,11 +324,6 @@ int usbip_recv(struct socket *sock, void
 	} while (msg_data_left(&msg));
 
 	if (usbip_dbg_flag_xmit) {
-		if (!in_interrupt())
-			pr_debug("%-10s:", current->comm);
-		else
-			pr_debug("interrupt  :");
-
 		pr_debug("receiving....\n");
 		usbip_dump_buffer(buf, size);
 		pr_debug("received, osize %d ret %d size %zd total %d\n",


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 08/13] usb: hosts: Remove in_interrupt() from comments
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
                   ` (6 preceding siblings ...)
  2020-10-19 10:06 ` [patch V2 07/13] usbip: Remove in_interrupt() check Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-19 16:28   ` Alan Stern
  2020-10-19 10:06 ` [patch V2 09/13] USB: host: ehci-pmcmsp: Cleanup usb_hcd_msp_remove() Thomas Gleixner
                   ` (4 subsequent siblings)
  12 siblings, 1 reply; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Alan Stern, Greg Kroah-Hartman, linux-usb, linux-omap,
	Kukjin Kim, Krzysztof Kozlowski, linux-arm-kernel,
	linux-samsung-soc, Thomas Winischhofer, Johan Hovold,
	Mathias Nyman, Valentina Manea, Shuah Khan, Felipe Balbi,
	Duncan Sands

From: Ahmed S. Darwish <a.darwish@linutronix.de>

The usage of in_interrupt() in drivers is phased out for various reasons.

Various comments use !in_interrupt() to describe calling context for probe()
and remove() functions. That's wrong because the calling context has to be
preemptible task context, which is not what !in_interrupt() describes.

Cleanup the comments. While at it add the missing kernel doc argument
descriptors.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>                                                                                                                                                                                                                                 
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Cc: linux-omap@vger.kernel.org
Cc: Kukjin Kim <kgene@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
---
V2: Split out the static change and add a missing comment
---
 drivers/usb/host/ehci-fsl.c     |    9 ++++-----
 drivers/usb/host/ehci-pmcmsp.c  |   11 +++++++----
 drivers/usb/host/ohci-at91.c    |   11 ++++++++---
 drivers/usb/host/ohci-omap.c    |    9 ++++++---
 drivers/usb/host/ohci-pxa27x.c  |   11 ++++++-----
 drivers/usb/host/ohci-s3c2410.c |   12 ++++++------
 6 files changed, 37 insertions(+), 26 deletions(-)

--- a/drivers/usb/host/ehci-fsl.c
+++ b/drivers/usb/host/ehci-fsl.c
@@ -39,10 +39,10 @@ static struct hc_driver __read_mostly fs
 /*
  * fsl_ehci_drv_probe - initialize FSL-based HCDs
  * @pdev: USB Host Controller being probed
- * Context: !in_interrupt()
  *
- * Allocates basic resources for this USB host controller.
+ * Context: task context, might sleep
  *
+ * Allocates basic resources for this USB host controller.
  */
 static int fsl_ehci_drv_probe(struct platform_device *pdev)
 {
@@ -684,12 +684,11 @@ static const struct ehci_driver_override
 /**
  * fsl_ehci_drv_remove - shutdown processing for FSL-based HCDs
  * @pdev: USB Host Controller being removed
- * Context: !in_interrupt()
  *
- * Reverses the effect of usb_hcd_fsl_probe().
+ * Context: task context, might sleep
  *
+ * Reverses the effect of usb_hcd_fsl_probe().
  */
-
 static int fsl_ehci_drv_remove(struct platform_device *pdev)
 {
 	struct fsl_usb2_platform_data *pdata = dev_get_platdata(&pdev->dev);
--- a/drivers/usb/host/ehci-pmcmsp.c
+++ b/drivers/usb/host/ehci-pmcmsp.c
@@ -147,12 +147,14 @@ static int usb_hcd_msp_map_regs(struct m
 
 /**
  * usb_hcd_msp_probe - initialize PMC MSP-based HCDs
- * Context: !in_interrupt()
+ * @driver:	Pointer to hc driver instance
+ * @dev:	USB controller to probe
+ *
+ * Context: task context, might sleep
  *
  * Allocates basic resources for this USB host controller, and
  * then invokes the start() method for the HCD associated with it
  * through the hotplug entry's driver_data.
- *
  */
 int usb_hcd_msp_probe(const struct hc_driver *driver,
 			  struct platform_device *dev)
@@ -223,8 +225,9 @@ int usb_hcd_msp_probe(const struct hc_dr
 
 /**
  * usb_hcd_msp_remove - shutdown processing for PMC MSP-based HCDs
- * @dev: USB Host Controller being removed
- * Context: !in_interrupt()
+ * @hcd: USB Host Controller being removed
+ *
+ * Context: task context, might sleep
  *
  * Reverses the effect of usb_hcd_msp_probe(), first invoking
  * the HCD's stop() method.  It is always called from a thread
--- a/drivers/usb/host/ohci-at91.c
+++ b/drivers/usb/host/ohci-at91.c
@@ -155,7 +155,10 @@ static struct regmap *at91_dt_syscon_sfr
 
 /*
  * usb_hcd_at91_probe - initialize AT91-based HCDs
- * Context: !in_interrupt()
+ * @driver:	Pointer to hc driver instance
+ * @pdev:	USB controller to probe
+ *
+ * Context: task context, might sleep
  *
  * Allocates basic resources for this USB host controller, and
  * then invokes the start() method for the HCD associated with it
@@ -246,12 +249,14 @@ static int usb_hcd_at91_probe(const stru
 
 /*
  * usb_hcd_at91_remove - shutdown processing for AT91-based HCDs
- * Context: !in_interrupt()
+ * @hcd:	USB controller to remove
+ * @pdev:	Platform device required for cleanup
+ *
+ * Context: task context, might sleep
  *
  * Reverses the effect of usb_hcd_at91_probe(), first invoking
  * the HCD's stop() method.  It is always called from a thread
  * context, "rmmod" or something similar.
- *
  */
 static void usb_hcd_at91_remove(struct usb_hcd *hcd,
 				struct platform_device *pdev)
--- a/drivers/usb/host/ohci-omap.c
+++ b/drivers/usb/host/ohci-omap.c
@@ -285,7 +285,9 @@ static int ohci_omap_reset(struct usb_hc
 
 /**
  * ohci_hcd_omap_probe - initialize OMAP-based HCDs
- * Context: !in_interrupt()
+ * @pdev:	USB controller to probe
+ *
+ * Context: task context, might sleep
  *
  * Allocates basic resources for this USB host controller, and
  * then invokes the start() method for the HCD associated with it
@@ -399,8 +401,9 @@ static int ohci_hcd_omap_probe(struct pl
 
 /**
  * ohci_hcd_omap_remove - shutdown processing for OMAP-based HCDs
- * @dev: USB Host Controller being removed
- * Context: !in_interrupt()
+ * @pdev: USB Host Controller being removed
+ *
+ * Context: task context, might sleep
  *
  * Reverses the effect of ohci_hcd_omap_probe(), first invoking
  * the HCD's stop() method.  It is always called from a thread
--- a/drivers/usb/host/ohci-pxa27x.c
+++ b/drivers/usb/host/ohci-pxa27x.c
@@ -410,12 +410,13 @@ static int ohci_pxa_of_init(struct platf
 
 /**
  * ohci_hcd_pxa27x_probe - initialize pxa27x-based HCDs
- * Context: !in_interrupt()
+ * @pdev:	USB Host controller to probe
+ *
+ * Context: task context, might sleep
  *
  * Allocates basic resources for this USB host controller, and
  * then invokes the start() method for the HCD associated with it
  * through the hotplug entry's driver_data.
- *
  */
 static int ohci_hcd_pxa27x_probe(struct platform_device *pdev)
 {
@@ -509,13 +510,13 @@ static int ohci_hcd_pxa27x_probe(struct
 
 /**
  * ohci_hcd_pxa27x_remove - shutdown processing for pxa27x-based HCDs
- * @dev: USB Host Controller being removed
- * Context: !in_interrupt()
+ * @pdev: USB Host Controller being removed
+ *
+ * Context: task context, might sleep
  *
  * Reverses the effect of ohci_hcd_pxa27x_probe(), first invoking
  * the HCD's stop() method.  It is always called from a thread
  * context, normally "rmmod", "apmd", or something similar.
- *
  */
 static int ohci_hcd_pxa27x_remove(struct platform_device *pdev)
 {
--- a/drivers/usb/host/ohci-s3c2410.c
+++ b/drivers/usb/host/ohci-s3c2410.c
@@ -324,14 +324,13 @@ static void s3c2410_hcd_oc(struct s3c241
 /*
  * ohci_hcd_s3c2410_remove - shutdown processing for HCD
  * @dev: USB Host Controller being removed
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep
  *
  * Reverses the effect of ohci_hcd_3c2410_probe(), first invoking
  * the HCD's stop() method.  It is always called from a thread
  * context, normally "rmmod", "apmd", or something similar.
- *
-*/
-
+ */
 static int
 ohci_hcd_s3c2410_remove(struct platform_device *dev)
 {
@@ -345,12 +344,13 @@ ohci_hcd_s3c2410_remove(struct platform_
 
 /*
  * ohci_hcd_s3c2410_probe - initialize S3C2410-based HCDs
- * Context: !in_interrupt()
+ * @dev: USB Host Controller to be probed
+ *
+ * Context: task context, might sleep
  *
  * Allocates basic resources for this USB host controller, and
  * then invokes the start() method for the HCD associated with it
  * through the hotplug entry's driver_data.
- *
  */
 static int ohci_hcd_s3c2410_probe(struct platform_device *dev)
 {


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 09/13] USB: host: ehci-pmcmsp: Cleanup usb_hcd_msp_remove()
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
                   ` (7 preceding siblings ...)
  2020-10-19 10:06 ` [patch V2 08/13] usb: hosts: Remove in_interrupt() from comments Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-19 16:28   ` Alan Stern
  2020-10-19 10:06 ` [patch V2 10/13] usb: gadget: pxa27x_udc: Replace in_interrupt() usage in comments Thomas Gleixner
                   ` (3 subsequent siblings)
  12 siblings, 1 reply; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Thomas Winischhofer, Greg Kroah-Hartman,
	linux-usb, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Johan Hovold, Mathias Nyman, Valentina Manea, Shuah Khan,
	Alan Stern, linux-omap, Kukjin Kim, Krzysztof Kozlowski,
	linux-arm-kernel, linux-samsung-soc, Felipe Balbi, Duncan Sands

usb_hcd_msp_remove() has a pdev argument which isn't used and the function
is used only within this file.

Remove pdev and make usb_hcd_msp_remove() static.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
V2: Split out from comments patch
---
 drivers/usb/host/ehci-pmcmsp.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/usb/host/ehci-pmcmsp.c
+++ b/drivers/usb/host/ehci-pmcmsp.c
@@ -236,7 +236,7 @@ int usb_hcd_msp_probe(const struct hc_dr
  * may be called without controller electrically present
  * may be called with controller, bus, and devices active
  */
-void usb_hcd_msp_remove(struct usb_hcd *hcd, struct platform_device *dev)
+static void usb_hcd_msp_remove(struct usb_hcd *hcd)
 {
 	usb_remove_hcd(hcd);
 	iounmap(hcd->regs);
@@ -309,7 +309,7 @@ static int ehci_hcd_msp_drv_remove(struc
 {
 	struct usb_hcd *hcd = platform_get_drvdata(pdev);
 
-	usb_hcd_msp_remove(hcd, pdev);
+	usb_hcd_msp_remove(hcd);
 
 	/* free TWI GPIO USB_HOST_DEV pin */
 	gpio_free(MSP_PIN_USB0_HOST_DEV);


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 10/13] usb: gadget: pxa27x_udc: Replace in_interrupt() usage in comments
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
                   ` (8 preceding siblings ...)
  2020-10-19 10:06 ` [patch V2 09/13] USB: host: ehci-pmcmsp: Cleanup usb_hcd_msp_remove() Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-19 10:06 ` [patch V2 11/13] usb: gadget: udc: Remove in_interrupt()/in_irq() from comments Thomas Gleixner
                   ` (2 subsequent siblings)
  12 siblings, 0 replies; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Felipe Balbi, Greg Kroah-Hartman, linux-arm-kernel, linux-usb,
	Thomas Winischhofer, Johan Hovold, Mathias Nyman,
	Valentina Manea, Shuah Khan, Alan Stern, linux-omap, Kukjin Kim,
	Krzysztof Kozlowski, linux-samsung-soc, Duncan Sands

From: Ahmed S. Darwish <a.darwish@linutronix.de>

The usage of in_interrupt() in drivers is phased out for various reasons.

Documenting calling contexts of functions with 'in_interrupt()' or
'!in_interrupt()' is imprecise: For a function which might sleep the
condition is preemptible task context, which is not what '!in_interrupt()'
describes.

Replace the context docummentation with plain text and make them match
reality.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-usb@vger.kernel.org

---
 drivers/usb/gadget/udc/pxa27x_udc.c |   19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

--- a/drivers/usb/gadget/udc/pxa27x_udc.c
+++ b/drivers/usb/gadget/udc/pxa27x_udc.c
@@ -304,7 +304,7 @@ static struct pxa_ep *find_pxa_ep(struct
  * update_pxa_ep_matches - update pxa_ep cached values in all udc_usb_ep
  * @udc: pxa udc
  *
- * Context: in_interrupt()
+ * Context: interrupt handler
  *
  * Updates all pxa_ep fields in udc_usb_ep structures, if this field was
  * previously set up (and is not NULL). The update is necessary is a
@@ -859,7 +859,7 @@ static int write_packet(struct pxa_ep *e
  * @ep: pxa physical endpoint
  * @req: usb request
  *
- * Context: callable when in_interrupt()
+ * Context: interrupt handler
  *
  * Unload as many packets as possible from the fifo we use for usb OUT
  * transfers and put them into the request. Caller should have made sure
@@ -997,7 +997,7 @@ static int read_ep0_fifo(struct pxa_ep *
  * @ep: control endpoint
  * @req: request
  *
- * Context: callable when in_interrupt()
+ * Context: interrupt handler
  *
  * Sends a request (or a part of the request) to the control endpoint (ep0 in).
  * If the request doesn't fit, the remaining part will be sent from irq.
@@ -1036,8 +1036,8 @@ static int write_ep0_fifo(struct pxa_ep
  * @_req: usb request
  * @gfp_flags: flags
  *
- * Context: normally called when !in_interrupt, but callable when in_interrupt()
- * in the special case of ep0 setup :
+ * Context: thread context or from the interrupt handler in the
+ * special case of ep0 setup :
  *   (irq->handle_ep0_ctrl_req->gadget_setup->pxa_ep_queue)
  *
  * Returns 0 if succedeed, error otherwise
@@ -1512,7 +1512,8 @@ static int should_disable_udc(struct pxa
  * pxa_udc_pullup - Offer manual D+ pullup control
  * @_gadget: usb gadget using the control
  * @is_active: 0 if disconnect, else connect D+ pullup resistor
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep
  *
  * Returns 0 if OK, -EOPNOTSUPP if udc driver doesn't handle D+ pullup
  */
@@ -1560,7 +1561,7 @@ static int pxa_udc_vbus_session(struct u
  * @_gadget: usb gadget
  * @mA: current drawn
  *
- * Context: !in_interrupt()
+ * Context: task context, might sleep
  *
  * Called after a configuration was chosen by a USB host, to inform how much
  * current can be drawn by the device from VBus line.
@@ -1886,7 +1887,7 @@ static void handle_ep0_ctrl_req(struct p
  * @fifo_irq: 1 if triggered by fifo service type irq
  * @opc_irq: 1 if triggered by output packet complete type irq
  *
- * Context : when in_interrupt() or with ep->lock held
+ * Context : interrupt handler
  *
  * Tries to transfer all pending request data into the endpoint and/or
  * transfer all pending data in the endpoint into usb requests.
@@ -2011,7 +2012,7 @@ static void handle_ep0(struct pxa_udc *u
  * Tries to transfer all pending request data into the endpoint and/or
  * transfer all pending data in the endpoint into usb requests.
  *
- * Is always called when in_interrupt() and with ep->lock released.
+ * Is always called from the interrupt handler. ep->lock must not be held.
  */
 static void handle_ep(struct pxa_ep *ep)
 {


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 11/13] usb: gadget: udc: Remove in_interrupt()/in_irq() from comments
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
                   ` (9 preceding siblings ...)
  2020-10-19 10:06 ` [patch V2 10/13] usb: gadget: pxa27x_udc: Replace in_interrupt() usage in comments Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-19 16:28   ` Alan Stern
  2020-10-19 10:06 ` [patch V2 12/13] usb: core: Replace in_interrupt() in comments Thomas Gleixner
  2020-10-19 10:06 ` [patch V2 13/13] usb: atm: Replace in_interrupt() usage in comment Thomas Gleixner
  12 siblings, 1 reply; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Felipe Balbi, Greg Kroah-Hartman, linux-usb, Thomas Winischhofer,
	Johan Hovold, Mathias Nyman, Valentina Manea, Shuah Khan,
	Alan Stern, linux-omap, Kukjin Kim, Krzysztof Kozlowski,
	linux-arm-kernel, linux-samsung-soc, Duncan Sands

From: Ahmed S. Darwish <a.darwish@linutronix.de>

The usage of in_irq()/in_interrupt() in drivers is phased out for various
reasons.

The context description for usb_gadget_giveback_request() is misleading as
in_interupt() means: hard interrupt or soft interrupt or bottom half
disabled regions. But it's also invoked from task context when endpoints
are torn down. Remove it as it's more confusing than helpful.

Replace also the in_irq() comment with plain text.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org

---
 drivers/usb/gadget/udc/core.c      |    2 --
 drivers/usb/gadget/udc/dummy_hcd.c |    6 ++++--
 2 files changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -894,8 +894,6 @@ EXPORT_SYMBOL_GPL(usb_gadget_unmap_reque
  * @ep: the endpoint to be used with with the request
  * @req: the request being given back
  *
- * Context: in_interrupt()
- *
  * This is called by device controller drivers in order to return the
  * completed request back to the gadget layer.
  */
--- a/drivers/usb/gadget/udc/dummy_hcd.c
+++ b/drivers/usb/gadget/udc/dummy_hcd.c
@@ -1754,8 +1754,10 @@ static int handle_control_request(struct
 	return ret_val;
 }
 
-/* drive both sides of the transfers; looks like irq handlers to
- * both drivers except the callbacks aren't in_irq().
+/*
+ * Drive both sides of the transfers; looks like irq handlers to both
+ * drivers except that the callbacks are invoked from soft interrupt
+ * context.
  */
 static void dummy_timer(struct timer_list *t)
 {


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 12/13] usb: core: Replace in_interrupt() in comments
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
                   ` (10 preceding siblings ...)
  2020-10-19 10:06 ` [patch V2 11/13] usb: gadget: udc: Remove in_interrupt()/in_irq() from comments Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-19 16:28   ` Alan Stern
  2020-10-19 10:06 ` [patch V2 13/13] usb: atm: Replace in_interrupt() usage in comment Thomas Gleixner
  12 siblings, 1 reply; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Greg Kroah-Hartman, linux-usb, Thomas Winischhofer, Johan Hovold,
	Mathias Nyman, Valentina Manea, Shuah Khan, Alan Stern,
	linux-omap, Kukjin Kim, Krzysztof Kozlowski, linux-arm-kernel,
	linux-samsung-soc, Felipe Balbi, Duncan Sands

From: Ahmed S. Darwish <a.darwish@linutronix.de>

The usage of in_interrupt() in drivers is phased out for various reasons.

Various comments use !in_interrupt() to describe calling context for
functions which might sleep. That's wrong because the calling context has
to be preemptible task context, which is not what !in_interrupt()
describes.

Replace !in_interrupt() with more accurate plain text descriptions.

The comment for usb_hcd_poll_rh_status() is misleading as this function is
called from all kinds of contexts including preemptible task
context. Remove it as there is obviously no restriction.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
---
V2: Fixup the comments according to review (Alan)
---
 drivers/usb/core/buffer.c  |    6 ++++--
 drivers/usb/core/hcd-pci.c |    6 ++++--
 drivers/usb/core/hcd.c     |   26 +++++++++++++++++---------
 drivers/usb/core/hub.c     |    3 ++-
 drivers/usb/core/message.c |   35 ++++++++++++++++++++++-------------
 drivers/usb/core/usb.c     |    4 ++--
 6 files changed, 51 insertions(+), 29 deletions(-)

--- a/drivers/usb/core/buffer.c
+++ b/drivers/usb/core/buffer.c
@@ -51,7 +51,8 @@ void __init usb_init_pool_max(void)
 /**
  * hcd_buffer_create - initialize buffer pools
  * @hcd: the bus whose buffer pools are to be initialized
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep
  *
  * Call this as part of initializing a host controller that uses the dma
  * memory allocators.  It initializes some pools of dma-coherent memory that
@@ -88,7 +89,8 @@ int hcd_buffer_create(struct usb_hcd *hc
 /**
  * hcd_buffer_destroy - deallocate buffer pools
  * @hcd: the bus whose buffer pools are to be destroyed
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep
  *
  * This frees the buffer pools created by hcd_buffer_create().
  */
--- a/drivers/usb/core/hcd-pci.c
+++ b/drivers/usb/core/hcd-pci.c
@@ -160,7 +160,8 @@ static void ehci_wait_for_companions(str
  * @dev: USB Host Controller being probed
  * @id: pci hotplug id connecting controller to HCD framework
  * @driver: USB HC driver handle
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep
  *
  * Allocates basic PCI resources for this USB host controller, and
  * then invokes the start() method for the HCD associated with it
@@ -304,7 +305,8 @@ EXPORT_SYMBOL_GPL(usb_hcd_pci_probe);
 /**
  * usb_hcd_pci_remove - shutdown processing for PCI-based HCDs
  * @dev: USB Host Controller being removed
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep
  *
  * Reverses the effect of usb_hcd_pci_probe(), first invoking
  * the HCD's stop() method.  It is always called from a thread
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -747,8 +747,7 @@ static int rh_call_control (struct usb_h
  * driver requests it; otherwise the driver is responsible for
  * calling usb_hcd_poll_rh_status() when an event occurs.
  *
- * Completions are called in_interrupt(), but they may or may not
- * be in_irq().
+ * Completion handler may not sleep. See usb_hcd_giveback_urb() for details.
  */
 void usb_hcd_poll_rh_status(struct usb_hcd *hcd)
 {
@@ -904,7 +903,8 @@ static void usb_bus_init (struct usb_bus
 /**
  * usb_register_bus - registers the USB host controller with the usb core
  * @bus: pointer to the bus to register
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep.
  *
  * Assigns a bus number, and links the controller into usbcore data
  * structures so that it can be seen by scanning the bus list.
@@ -939,7 +939,8 @@ static int usb_register_bus(struct usb_b
 /**
  * usb_deregister_bus - deregisters the USB host controller
  * @bus: pointer to the bus to deregister
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep.
  *
  * Recycles the bus number, and unlinks the controller from usbcore data
  * structures so that it won't be seen by scanning the bus list.
@@ -1691,7 +1692,11 @@ static void usb_giveback_urb_bh(unsigned
  * @hcd: host controller returning the URB
  * @urb: urb being returned to the USB device driver.
  * @status: completion status code for the URB.
- * Context: in_interrupt()
+ *
+ * Context: atomic. The completion callback is invoked in caller's context.
+ * For HCDs with HCD_BH flag set, the completion callback is invoked in tasklet
+ * context (except for URBs submitted to the root hub which always complete in
+ * caller's context).
  *
  * This hands the URB from HCD to its USB device driver, using its
  * completion function.  The HCD has freed all per-urb resources
@@ -2268,7 +2273,7 @@ EXPORT_SYMBOL_GPL(usb_hcd_resume_root_hu
  * usb_bus_start_enum - start immediate enumeration (for OTG)
  * @bus: the bus (must use hcd framework)
  * @port_num: 1-based number of port; usually bus->otg_port
- * Context: in_interrupt()
+ * Context: atomic
  *
  * Starts enumeration, with an immediate reset followed later by
  * hub_wq identifying and possibly configuring the device.
@@ -2474,7 +2479,8 @@ EXPORT_SYMBOL_GPL(__usb_create_hcd);
  * @bus_name: value to store in hcd->self.bus_name
  * @primary_hcd: a pointer to the usb_hcd structure that is sharing the
  *              PCI device.  Only allocate certain resources for the primary HCD
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep.
  *
  * Allocate a struct usb_hcd, with extra space at the end for the
  * HC driver's private data.  Initialize the generic members of the
@@ -2496,7 +2502,8 @@ EXPORT_SYMBOL_GPL(usb_create_shared_hcd)
  * @driver: HC driver that will use this hcd
  * @dev: device for this HC, stored in hcd->self.controller
  * @bus_name: value to store in hcd->self.bus_name
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep.
  *
  * Allocate a struct usb_hcd, with extra space at the end for the
  * HC driver's private data.  Initialize the generic members of the
@@ -2830,7 +2837,8 @@ EXPORT_SYMBOL_GPL(usb_add_hcd);
 /**
  * usb_remove_hcd - shutdown processing for generic HCDs
  * @hcd: the usb_hcd structure to remove
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep.
  *
  * Disconnects the root hub, then reverses the effects of usb_add_hcd(),
  * invoking the HCD's stop() method.
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2171,7 +2171,8 @@ static void hub_disconnect_children(stru
 /**
  * usb_disconnect - disconnect a device (usbcore-internal)
  * @pdev: pointer to device being disconnected
- * Context: !in_interrupt ()
+ *
+ * Context: task context, might sleep
  *
  * Something got disconnected. Get rid of it and all of its children.
  *
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -119,7 +119,7 @@ static int usb_internal_control_msg(stru
  * @timeout: time in msecs to wait for the message to complete before timing
  *	out (if 0 the wait is forever)
  *
- * Context: !in_interrupt ()
+ * Context: task context, might sleep.
  *
  * This function sends a simple control message to a specified endpoint and
  * waits for the message to complete, or timeout.
@@ -173,7 +173,7 @@ EXPORT_SYMBOL_GPL(usb_control_msg);
  * @timeout: time in msecs to wait for the message to complete before
  *	timing out (if 0 the wait is forever)
  *
- * Context: !in_interrupt ()
+ * Context: task context, might sleep.
  *
  * This function sends a simple interrupt message to a specified endpoint and
  * waits for the message to complete, or timeout.
@@ -206,7 +206,7 @@ EXPORT_SYMBOL_GPL(usb_interrupt_msg);
  * @timeout: time in msecs to wait for the message to complete before
  *	timing out (if 0 the wait is forever)
  *
- * Context: !in_interrupt ()
+ * Context: task context, might sleep.
  *
  * This function sends a simple bulk message to a specified endpoint
  * and waits for the message to complete, or timeout.
@@ -473,7 +473,8 @@ EXPORT_SYMBOL_GPL(usb_sg_init);
  * usb_sg_wait - synchronously execute scatter/gather request
  * @io: request block handle, as initialized with usb_sg_init().
  * 	some fields become accessible when this call returns.
- * Context: !in_interrupt ()
+ *
+ * Context: task context, might sleep.
  *
  * This function blocks until the specified I/O operation completes.  It
  * leverages the grouping of the related I/O requests to get good transfer
@@ -627,7 +628,8 @@ EXPORT_SYMBOL_GPL(usb_sg_cancel);
  * @index: the number of the descriptor
  * @buf: where to put the descriptor
  * @size: how big is "buf"?
- * Context: !in_interrupt ()
+ *
+ * Context: task context, might sleep.
  *
  * Gets a USB descriptor.  Convenience functions exist to simplify
  * getting some types of descriptors.  Use
@@ -675,7 +677,8 @@ EXPORT_SYMBOL_GPL(usb_get_descriptor);
  * @index: the number of the descriptor
  * @buf: where to put the string
  * @size: how big is "buf"?
- * Context: !in_interrupt ()
+ *
+ * Context: task context, might sleep.
  *
  * Retrieves a string, encoded using UTF-16LE (Unicode, 16 bits per character,
  * in little-endian byte order).
@@ -810,7 +813,8 @@ static int usb_get_langid(struct usb_dev
  * @index: the number of the descriptor
  * @buf: where to put the string
  * @size: how big is "buf"?
- * Context: !in_interrupt ()
+ *
+ * Context: task context, might sleep.
  *
  * This converts the UTF-16LE encoded strings returned by devices, from
  * usb_get_string_descriptor(), to null-terminated UTF-8 encoded ones
@@ -899,7 +903,8 @@ char *usb_cache_string(struct usb_device
  * usb_get_device_descriptor - (re)reads the device descriptor (usbcore)
  * @dev: the device whose device descriptor is being updated
  * @size: how much of the descriptor to read
- * Context: !in_interrupt ()
+ *
+ * Context: task context, might sleep.
  *
  * Updates the copy of the device descriptor stored in the device structure,
  * which dedicates space for this purpose.
@@ -934,7 +939,7 @@ int usb_get_device_descriptor(struct usb
 /*
  * usb_set_isoch_delay - informs the device of the packet transmit delay
  * @dev: the device whose delay is to be informed
- * Context: !in_interrupt()
+ * Context: task context, might sleep
  *
  * Since this is an optional request, we don't bother if it fails.
  */
@@ -962,7 +967,8 @@ int usb_set_isoch_delay(struct usb_devic
  * @type: USB_STATUS_TYPE_*; for standard or PTM status types
  * @target: zero (for device), else interface or endpoint number
  * @data: pointer to two bytes of bitmap data
- * Context: !in_interrupt ()
+ *
+ * Context: task context, might sleep.
  *
  * Returns device, interface, or endpoint status.  Normally only of
  * interest to see if the device is self powered, or has enabled the
@@ -1039,7 +1045,8 @@ EXPORT_SYMBOL_GPL(usb_get_status);
  * usb_clear_halt - tells device to clear endpoint halt/stall condition
  * @dev: device whose endpoint is halted
  * @pipe: endpoint "pipe" being cleared
- * Context: !in_interrupt ()
+ *
+ * Context: task context, might sleep.
  *
  * This is used to clear halt conditions for bulk and interrupt endpoints,
  * as reported by URB completion status.  Endpoints that are halted are
@@ -1343,7 +1350,8 @@ void usb_enable_interface(struct usb_dev
  * @dev: the device whose interface is being updated
  * @interface: the interface being updated
  * @alternate: the setting being chosen.
- * Context: !in_interrupt ()
+ *
+ * Context: task context, might sleep.
  *
  * This is used to enable data transfers on interfaces that may not
  * be enabled by default.  Not all devices support such configurability.
@@ -1762,7 +1770,8 @@ static void __usb_queue_reset_device(str
  * usb_set_configuration - Makes a particular device setting be current
  * @dev: the device whose configuration is being updated
  * @configuration: the configuration being chosen.
- * Context: !in_interrupt(), caller owns the device lock
+ *
+ * Context: task context, might sleep. Caller holds device lock.
  *
  * This is used to enable non-default device modes.  Not all devices
  * use this kind of configurability; many devices only have one
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -28,7 +28,6 @@
 #include <linux/string.h>
 #include <linux/bitops.h>
 #include <linux/slab.h>
-#include <linux/interrupt.h>  /* for in_interrupt() */
 #include <linux/kmod.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
@@ -561,7 +560,8 @@ static bool usb_dev_authorized(struct us
  * @parent: hub to which device is connected; null to allocate a root hub
  * @bus: bus used to access the device
  * @port1: one-based index of port; ignored for root hubs
- * Context: !in_interrupt()
+ *
+ * Context: task context, might sleep.
  *
  * Only hub drivers (including virtual root hub drivers for host
  * controllers) should ever call this.


^ permalink raw reply	[flat|nested] 27+ messages in thread

* [patch V2 13/13] usb: atm: Replace in_interrupt() usage in comment
  2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
                   ` (11 preceding siblings ...)
  2020-10-19 10:06 ` [patch V2 12/13] usb: core: Replace in_interrupt() in comments Thomas Gleixner
@ 2020-10-19 10:06 ` Thomas Gleixner
  2020-10-19 10:28   ` Duncan Sands
  12 siblings, 1 reply; 27+ messages in thread
From: Thomas Gleixner @ 2020-10-19 10:06 UTC (permalink / raw)
  To: LKML
  Cc: Peter Zijlstra, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Duncan Sands, Greg Kroah-Hartman, linux-usb, Thomas Winischhofer,
	Johan Hovold, Mathias Nyman, Valentina Manea, Shuah Khan,
	Alan Stern, linux-omap, Kukjin Kim, Krzysztof Kozlowski,
	linux-arm-kernel, linux-samsung-soc, Felipe Balbi

in_interrupt() is a pretty vague context description as it means: hard
interrupt, soft interrupt or bottom half disabled regions.

Replace the vague comment with a proper reasoning why spin_lock_irqsave()
needs to be used.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Duncan Sands <duncan.sands@free.fr>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org

---
 drivers/usb/atm/usbatm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/atm/usbatm.c
+++ b/drivers/usb/atm/usbatm.c
@@ -249,7 +249,7 @@ static void usbatm_complete(struct urb *
 	/* vdbg("%s: urb 0x%p, status %d, actual_length %d",
 	     __func__, urb, status, urb->actual_length); */
 
-	/* usually in_interrupt(), but not always */
+	/* Can be invoked from task context, protect against interrupts */
 	spin_lock_irqsave(&channel->lock, flags);
 
 	/* must add to the back when receiving; doesn't matter when sending */


^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [patch V2 13/13] usb: atm: Replace in_interrupt() usage in comment
  2020-10-19 10:06 ` [patch V2 13/13] usb: atm: Replace in_interrupt() usage in comment Thomas Gleixner
@ 2020-10-19 10:28   ` Duncan Sands
  0 siblings, 0 replies; 27+ messages in thread
From: Duncan Sands @ 2020-10-19 10:28 UTC (permalink / raw)
  To: Thomas Gleixner, LKML
  Cc: Peter Zijlstra, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Greg Kroah-Hartman, linux-usb, Thomas Winischhofer, Johan Hovold,
	Mathias Nyman, Valentina Manea, Shuah Khan, Alan Stern,
	linux-omap, Kukjin Kim, Krzysztof Kozlowski, linux-arm-kernel,
	linux-samsung-soc, Felipe Balbi

On 10/19/20 12:06 PM, Thomas Gleixner wrote:
> in_interrupt() is a pretty vague context description as it means: hard
> interrupt, soft interrupt or bottom half disabled regions.
> 
> Replace the vague comment with a proper reasoning why spin_lock_irqsave()
> needs to be used.
> 
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Duncan Sands <duncan.sands@free.fr>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-usb@vger.kernel.org
> 
> ---
>   drivers/usb/atm/usbatm.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/drivers/usb/atm/usbatm.c
> +++ b/drivers/usb/atm/usbatm.c
> @@ -249,7 +249,7 @@ static void usbatm_complete(struct urb *
>   	/* vdbg("%s: urb 0x%p, status %d, actual_length %d",
>   	     __func__, urb, status, urb->actual_length); */
>   
> -	/* usually in_interrupt(), but not always */
> +	/* Can be invoked from task context, protect against interrupts */
>   	spin_lock_irqsave(&channel->lock, flags);
>   
>   	/* must add to the back when receiving; doesn't matter when sending */
> 


Signed-off-by: Duncan Sands <duncan.sands@free.fr>

^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [patch V2 08/13] usb: hosts: Remove in_interrupt() from comments
  2020-10-19 10:06 ` [patch V2 08/13] usb: hosts: Remove in_interrupt() from comments Thomas Gleixner
@ 2020-10-19 16:28   ` Alan Stern
  0 siblings, 0 replies; 27+ messages in thread
From: Alan Stern @ 2020-10-19 16:28 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: LKML, Peter Zijlstra, Ahmed S. Darwish,
	Sebastian Andrzej Siewior, Greg Kroah-Hartman, linux-usb,
	linux-omap, Kukjin Kim, Krzysztof Kozlowski, linux-arm-kernel,
	linux-samsung-soc, Thomas Winischhofer, Johan Hovold,
	Mathias Nyman, Valentina Manea, Shuah Khan, Felipe Balbi,
	Duncan Sands

On Mon, Oct 19, 2020 at 12:06:37PM +0200, Thomas Gleixner wrote:
> From: Ahmed S. Darwish <a.darwish@linutronix.de>
> 
> The usage of in_interrupt() in drivers is phased out for various reasons.
> 
> Various comments use !in_interrupt() to describe calling context for probe()
> and remove() functions. That's wrong because the calling context has to be
> preemptible task context, which is not what !in_interrupt() describes.
> 
> Cleanup the comments. While at it add the missing kernel doc argument
> descriptors.
> 
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Acked-by: Krzysztof Kozlowski <krzk@kernel.org>                                                                                                                                                                                                                                 
> Cc: Alan Stern <stern@rowland.harvard.edu>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-usb@vger.kernel.org
> Cc: linux-omap@vger.kernel.org
> Cc: Kukjin Kim <kgene@kernel.org>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-samsung-soc@vger.kernel.org
> ---
> V2: Split out the static change and add a missing comment
> ---
>  drivers/usb/host/ehci-fsl.c     |    9 ++++-----
>  drivers/usb/host/ehci-pmcmsp.c  |   11 +++++++----
>  drivers/usb/host/ohci-at91.c    |   11 ++++++++---
>  drivers/usb/host/ohci-omap.c    |    9 ++++++---
>  drivers/usb/host/ohci-pxa27x.c  |   11 ++++++-----
>  drivers/usb/host/ohci-s3c2410.c |   12 ++++++------
>  6 files changed, 37 insertions(+), 26 deletions(-)

Acked-by: Alan Stern <stern@rowland.harvard.edu>

^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [patch V2 09/13] USB: host: ehci-pmcmsp: Cleanup usb_hcd_msp_remove()
  2020-10-19 10:06 ` [patch V2 09/13] USB: host: ehci-pmcmsp: Cleanup usb_hcd_msp_remove() Thomas Gleixner
@ 2020-10-19 16:28   ` Alan Stern
  0 siblings, 0 replies; 27+ messages in thread
From: Alan Stern @ 2020-10-19 16:28 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: LKML, Peter Zijlstra, Thomas Winischhofer, Greg Kroah-Hartman,
	linux-usb, Ahmed S. Darwish, Sebastian Andrzej Siewior,
	Johan Hovold, Mathias Nyman, Valentina Manea, Shuah Khan,
	linux-omap, Kukjin Kim, Krzysztof Kozlowski, linux-arm-kernel,
	linux-samsung-soc, Felipe Balbi, Duncan Sands

On Mon, Oct 19, 2020 at 12:06:38PM +0200, Thomas Gleixner wrote:
> usb_hcd_msp_remove() has a pdev argument which isn't used and the function
> is used only within this file.
> 
> Remove pdev and make usb_hcd_msp_remove() static.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> V2: Split out from comments patch
> ---
>  drivers/usb/host/ehci-pmcmsp.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> --- a/drivers/usb/host/ehci-pmcmsp.c
> +++ b/drivers/usb/host/ehci-pmcmsp.c
> @@ -236,7 +236,7 @@ int usb_hcd_msp_probe(const struct hc_dr
>   * may be called without controller electrically present
>   * may be called with controller, bus, and devices active
>   */
> -void usb_hcd_msp_remove(struct usb_hcd *hcd, struct platform_device *dev)
> +static void usb_hcd_msp_remove(struct usb_hcd *hcd)
>  {
>  	usb_remove_hcd(hcd);
>  	iounmap(hcd->regs);
> @@ -309,7 +309,7 @@ static int ehci_hcd_msp_drv_remove(struc
>  {
>  	struct usb_hcd *hcd = platform_get_drvdata(pdev);
>  
> -	usb_hcd_msp_remove(hcd, pdev);
> +	usb_hcd_msp_remove(hcd);
>  
>  	/* free TWI GPIO USB_HOST_DEV pin */
>  	gpio_free(MSP_PIN_USB0_HOST_DEV);

Acked-by: Alan Stern <stern@rowland.harvard.edu>

^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [patch V2 11/13] usb: gadget: udc: Remove in_interrupt()/in_irq() from comments
  2020-10-19 10:06 ` [patch V2 11/13] usb: gadget: udc: Remove in_interrupt()/in_irq() from comments Thomas Gleixner
@ 2020-10-19 16:28   ` Alan Stern
  0 siblings, 0 replies; 27+ messages in thread
From: Alan Stern @ 2020-10-19 16:28 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: LKML, Peter Zijlstra, Ahmed S. Darwish,
	Sebastian Andrzej Siewior, Felipe Balbi, Greg Kroah-Hartman,
	linux-usb, Thomas Winischhofer, Johan Hovold, Mathias Nyman,
	Valentina Manea, Shuah Khan, linux-omap, Kukjin Kim,
	Krzysztof Kozlowski, linux-arm-kernel, linux-samsung-soc,
	Duncan Sands

On Mon, Oct 19, 2020 at 12:06:40PM +0200, Thomas Gleixner wrote:
> From: Ahmed S. Darwish <a.darwish@linutronix.de>
> 
> The usage of in_irq()/in_interrupt() in drivers is phased out for various
> reasons.
> 
> The context description for usb_gadget_giveback_request() is misleading as
> in_interupt() means: hard interrupt or soft interrupt or bottom half
> disabled regions. But it's also invoked from task context when endpoints
> are torn down. Remove it as it's more confusing than helpful.
> 
> Replace also the in_irq() comment with plain text.
> 
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Felipe Balbi <balbi@kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-usb@vger.kernel.org
> 
> ---
>  drivers/usb/gadget/udc/core.c      |    2 --
>  drivers/usb/gadget/udc/dummy_hcd.c |    6 ++++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -894,8 +894,6 @@ EXPORT_SYMBOL_GPL(usb_gadget_unmap_reque
>   * @ep: the endpoint to be used with with the request
>   * @req: the request being given back
>   *
> - * Context: in_interrupt()
> - *
>   * This is called by device controller drivers in order to return the
>   * completed request back to the gadget layer.
>   */
> --- a/drivers/usb/gadget/udc/dummy_hcd.c
> +++ b/drivers/usb/gadget/udc/dummy_hcd.c
> @@ -1754,8 +1754,10 @@ static int handle_control_request(struct
>  	return ret_val;
>  }
>  
> -/* drive both sides of the transfers; looks like irq handlers to
> - * both drivers except the callbacks aren't in_irq().
> +/*
> + * Drive both sides of the transfers; looks like irq handlers to both
> + * drivers except that the callbacks are invoked from soft interrupt
> + * context.
>   */
>  static void dummy_timer(struct timer_list *t)
>  {

For dummy-hcd.c:

Acked-by: Alan Stern <stern@rowland.harvard.edu>


^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [patch V2 12/13] usb: core: Replace in_interrupt() in comments
  2020-10-19 10:06 ` [patch V2 12/13] usb: core: Replace in_interrupt() in comments Thomas Gleixner
@ 2020-10-19 16:28   ` Alan Stern
  0 siblings, 0 replies; 27+ messages in thread
From: Alan Stern @ 2020-10-19 16:28 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: LKML, Peter Zijlstra, Ahmed S. Darwish,
	Sebastian Andrzej Siewior, Greg Kroah-Hartman, linux-usb,
	Thomas Winischhofer, Johan Hovold, Mathias Nyman,
	Valentina Manea, Shuah Khan, linux-omap, Kukjin Kim,
	Krzysztof Kozlowski, linux-arm-kernel, linux-samsung-soc,
	Felipe Balbi, Duncan Sands

On Mon, Oct 19, 2020 at 12:06:41PM +0200, Thomas Gleixner wrote:
> From: Ahmed S. Darwish <a.darwish@linutronix.de>
> 
> The usage of in_interrupt() in drivers is phased out for various reasons.
> 
> Various comments use !in_interrupt() to describe calling context for
> functions which might sleep. That's wrong because the calling context has
> to be preemptible task context, which is not what !in_interrupt()
> describes.
> 
> Replace !in_interrupt() with more accurate plain text descriptions.
> 
> The comment for usb_hcd_poll_rh_status() is misleading as this function is
> called from all kinds of contexts including preemptible task
> context. Remove it as there is obviously no restriction.
> 
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-usb@vger.kernel.org
> ---
> V2: Fixup the comments according to review (Alan)
> ---
>  drivers/usb/core/buffer.c  |    6 ++++--
>  drivers/usb/core/hcd-pci.c |    6 ++++--
>  drivers/usb/core/hcd.c     |   26 +++++++++++++++++---------
>  drivers/usb/core/hub.c     |    3 ++-
>  drivers/usb/core/message.c |   35 ++++++++++++++++++++++-------------
>  drivers/usb/core/usb.c     |    4 ++--
>  6 files changed, 51 insertions(+), 29 deletions(-)

Acked-by: Alan Stern <stern@rowland.harvard.edu>

^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage
  2020-10-19 10:06 ` [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage Thomas Gleixner
@ 2020-10-25 16:56   ` Johan Hovold
  2020-10-26 12:47     ` Sebastian Andrzej Siewior
  0 siblings, 1 reply; 27+ messages in thread
From: Johan Hovold @ 2020-10-25 16:56 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: LKML, Peter Zijlstra, Ahmed S. Darwish,
	Sebastian Andrzej Siewior, Johan Hovold, Greg Kroah-Hartman,
	linux-usb, Thomas Winischhofer, Mathias Nyman, Valentina Manea,
	Shuah Khan, Alan Stern, linux-omap, Kukjin Kim,
	Krzysztof Kozlowski, linux-arm-kernel, linux-samsung-soc,
	Felipe Balbi, Duncan Sands

On Mon, Oct 19, 2020 at 12:06:31PM +0200, Thomas Gleixner wrote:
> keyspan_pda_write() uses in_interrupt() to check whether it is safe to
> invoke functions which might sleep.
> 
> The usage of in_interrupt() in drivers is phased out and Linus clearly
> requested that code which changes behaviour depending on context should
> either be seperated or the context be conveyed in an argument passed by the
> caller, which usually knows the context.
> 
> Aside of that it does not cover all contexts which cannot sleep,
> e.g. preempt disabled regions which cannot be reliably detected on all
> kernel configurations.
> 
> With the current printk() implementation console->write() can be invoked
> from almost any context. The upcoming rework of the console core will
> provide thread context for console drivers which require to sleep.
> 
> For now, restrict the room query which can sleep to tty writes which happen
> from preemptible task context.
> 
> The usability for dmesg output is limited anyway because it's almost
> guaranteed to drop the 'LF' which is submitted after the dmesg line because
> the device supports only one transfer on flight. Same for any printk()
> which is coming in before the previous transfer has been done.
> 
> This new restriction does not make it worse than before, but it makes the
> condition correct under all circumstances.
> 
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Johan Hovold <johan@kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-usb@vger.kernel.org
> 
> ---
>  drivers/usb/serial/keyspan_pda.c |   10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> --- a/drivers/usb/serial/keyspan_pda.c
> +++ b/drivers/usb/serial/keyspan_pda.c
> @@ -477,10 +477,12 @@ static int keyspan_pda_write(struct tty_
>  
>  	count = (count > port->bulk_out_size) ? port->bulk_out_size : count;
>  
> -	/* Check if we might overrun the Tx buffer.   If so, ask the
> -	   device how much room it really has.  This is done only on
> -	   scheduler time, since usb_control_msg() sleeps. */
> -	if (count > priv->tx_room && !in_interrupt()) {
> +	/*
> +	 * Check if we might overrun the Tx buffer. If so, ask the device
> +	 * how much room it really has. This can only be invoked for tty
> +	 * usage because the console write can't sleep.
> +	 */
> +	if (count > priv->tx_room && tty) {
>  		u8 *room;
>  
>  		room = kmalloc(1, GFP_KERNEL);

There's a ton of issues with this driver, but this is arguably making
things worse. A line discipline may call write() from just about any
context so we cannot rely on tty being non-NULL here (e.g. PPP).

I've prepared a series fixing up the driver's write implementation
that does away with this room check in the write path instead.

Johan

^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [patch V2 03/13] USB: serial: keyspan_pda: Consolidate room query
  2020-10-19 10:06 ` [patch V2 03/13] USB: serial: keyspan_pda: Consolidate room query Thomas Gleixner
@ 2020-10-25 17:05   ` Johan Hovold
  0 siblings, 0 replies; 27+ messages in thread
From: Johan Hovold @ 2020-10-25 17:05 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: LKML, Peter Zijlstra, Sebastian Andrzej Siewior, Johan Hovold,
	Greg Kroah-Hartman, linux-usb, Thomas Winischhofer,
	Ahmed S. Darwish, Mathias Nyman, Valentina Manea, Shuah Khan,
	Alan Stern, linux-omap, Kukjin Kim, Krzysztof Kozlowski,
	linux-arm-kernel, linux-samsung-soc, Felipe Balbi, Duncan Sands

On Mon, Oct 19, 2020 at 12:06:32PM +0200, Thomas Gleixner wrote:
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> 
> Having two copies of the same code doesn't make the code more readable and
> allocating a buffer of 1 byte for a synchronous operation is a pointless
> exercise.

As Alan pointed out, this buffer is in fact required and not pointless
at all even if reallocating it may be suboptimal.

Note however that there are several further allocations done by
usb_control_msg() for each control request.

> Allocate a byte buffer at init which can be used instead. The buffer is
> only used in open() and tty->write(). Console writes are not calling into
> the query. open() obviously happens before write() and the writes are
> serialized by bit 0 of port->write_urbs_free which protects also the
> transaction itself.

As I mentioned in my comments to the previous patch, I've rewritten the
driver so that is no longer does this query in the write path. I kept
the buffer allocation for now though in case you want to rework this one
top.

Johan

^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [patch V2 04/13] USB: serial: digi_acceleport: Remove in_interrupt() usage
  2020-10-19 10:06 ` [patch V2 04/13] USB: serial: digi_acceleport: Remove in_interrupt() usage Thomas Gleixner
@ 2020-10-25 17:16   ` Johan Hovold
  2020-10-26 14:03     ` [PATCH v3 04/13 ] " Sebastian Andrzej Siewior
  0 siblings, 1 reply; 27+ messages in thread
From: Johan Hovold @ 2020-10-25 17:16 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: LKML, Peter Zijlstra, Ahmed S. Darwish,
	Sebastian Andrzej Siewior, Johan Hovold, Greg Kroah-Hartman,
	linux-usb, Thomas Winischhofer, Mathias Nyman, Valentina Manea,
	Shuah Khan, Alan Stern, linux-omap, Kukjin Kim,
	Krzysztof Kozlowski, linux-arm-kernel, linux-samsung-soc,
	Felipe Balbi, Duncan Sands

On Mon, Oct 19, 2020 at 12:06:33PM +0200, Thomas Gleixner wrote:
> From: Ahmed S. Darwish <a.darwish@linutronix.de>
> 
> The usage of in_interrupt() in drivers is phased out and Linus clearly
> requested that code which changes behaviour depending on context should
> either be separated or the context be conveyed in an argument passed by the
> caller, which usually knows the context.
> 
> The debug printk() in digi_write() prints in_interrupt() as context
> information. TTY writes happen always in preemptible task context and
> console writes can happen from almost any context, so in_interrupt() is not
> really helpful.

The above statement is not correct, TTY writes can and do happen from
other contexts, including soft IRQ (e.g. PPP).

> Aside of that issuing a printk() from a console->write() callback is not a
> really brilliant idea for obvious reasons.

True, but we don't need to sprinkle conditionals for the benefit of
people trying to debug USB serial drivers using a USB serial console.
They get what they deserve. ;)

> Remove the in_interrupt() printout and make the printk() depend on tty.
> 
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Johan Hovold <johan@kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-usb@vger.kernel.org
> 
> ---
>  drivers/usb/serial/digi_acceleport.c |    7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> --- a/drivers/usb/serial/digi_acceleport.c
> +++ b/drivers/usb/serial/digi_acceleport.c
> @@ -911,9 +911,10 @@ static int digi_write(struct tty_struct
>  	unsigned char *data = port->write_urb->transfer_buffer;
>  	unsigned long flags = 0;
>  
> -	dev_dbg(&port->dev,
> -		"digi_write: TOP: port=%d, count=%d, in_interrupt=%ld\n",
> -		priv->dp_port_num, count, in_interrupt());
> +	if (tty) {
> +		dev_dbg(&port->dev, "digi_write: TOP: port=%d, count=%d\n",
> +			priv->dp_port_num, count);
> +	}

So just drop the in_interrupt() here.

Also note that we already have another unconditional dev_dbg() at the
end of this function.

>  
>  	/* copy user data (which can sleep) before getting spin lock */
>  	count = min(count, port->bulk_out_size-2);
> 

Johan

^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage
  2020-10-25 16:56   ` Johan Hovold
@ 2020-10-26 12:47     ` Sebastian Andrzej Siewior
  2020-10-27  8:16       ` Johan Hovold
  0 siblings, 1 reply; 27+ messages in thread
From: Sebastian Andrzej Siewior @ 2020-10-26 12:47 UTC (permalink / raw)
  To: Johan Hovold
  Cc: Thomas Gleixner, LKML, Peter Zijlstra, Ahmed S. Darwish,
	Greg Kroah-Hartman, linux-usb, Thomas Winischhofer,
	Mathias Nyman, Valentina Manea, Shuah Khan, Alan Stern,
	linux-omap, Kukjin Kim, Krzysztof Kozlowski, linux-arm-kernel,
	linux-samsung-soc, Felipe Balbi, Duncan Sands

On 2020-10-25 17:56:47 [+0100], Johan Hovold wrote:
> There's a ton of issues with this driver, but this is arguably making
> things worse. A line discipline may call write() from just about any
> context so we cannot rely on tty being non-NULL here (e.g. PPP).

I wasn't aware of that. I've been looking at the callers each time a
`tty' was passed it looked like a preemptible context (due to mutex /
GFP_KERNEL) and so on.

> 
> Johan

Sebastian

^ permalink raw reply	[flat|nested] 27+ messages in thread

* [PATCH v3 04/13 ] USB: serial: digi_acceleport: Remove in_interrupt() usage
  2020-10-25 17:16   ` Johan Hovold
@ 2020-10-26 14:03     ` Sebastian Andrzej Siewior
  2020-10-27  8:26       ` Johan Hovold
  0 siblings, 1 reply; 27+ messages in thread
From: Sebastian Andrzej Siewior @ 2020-10-26 14:03 UTC (permalink / raw)
  To: Johan Hovold
  Cc: Thomas Gleixner, LKML, Peter Zijlstra, Ahmed S. Darwish,
	Greg Kroah-Hartman, linux-usb, Thomas Winischhofer,
	Mathias Nyman, Valentina Manea, Shuah Khan, Alan Stern,
	linux-omap, Kukjin Kim, Krzysztof Kozlowski, linux-arm-kernel,
	linux-samsung-soc, Felipe Balbi, Duncan Sands

From: "Ahmed S. Darwish" <a.darwish@linutronix.de>

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

The debug printk() in digi_write() prints in_interrupt() as context
information. This information is imprecisely as it does not distinguish
between hard-IRQ or disabled botton half and it does consider disabled
interrupts or preemption. It is not really helpful.

Remove the in_interrupt() printout.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Johan Hovold <johan@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
---
v2…v3:
  - Don't make dev_dbg() conditional on `tty'
  - Remove the part "tty happens always in process context" from the
    commit message. Johan pointed out that for PPP it may happen in
    bottom half.

 drivers/usb/serial/digi_acceleport.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/serial/digi_acceleport.c b/drivers/usb/serial/digi_acceleport.c
index 91055a191995f..016e7dec31962 100644
--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -911,9 +911,8 @@ static int digi_write(struct tty_struct *tty, struct usb_serial_port *port,
 	unsigned char *data = port->write_urb->transfer_buffer;
 	unsigned long flags = 0;
 
-	dev_dbg(&port->dev,
-		"digi_write: TOP: port=%d, count=%d, in_interrupt=%ld\n",
-		priv->dp_port_num, count, in_interrupt());
+	dev_dbg(&port->dev, "digi_write: TOP: port=%d, count=%d\n",
+		priv->dp_port_num, count);
 
 	/* copy user data (which can sleep) before getting spin lock */
 	count = min(count, port->bulk_out_size-2);
-- 
2.28.0


^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage
  2020-10-26 12:47     ` Sebastian Andrzej Siewior
@ 2020-10-27  8:16       ` Johan Hovold
  0 siblings, 0 replies; 27+ messages in thread
From: Johan Hovold @ 2020-10-27  8:16 UTC (permalink / raw)
  To: Sebastian Andrzej Siewior
  Cc: Johan Hovold, Thomas Gleixner, LKML, Peter Zijlstra,
	Ahmed S. Darwish, Greg Kroah-Hartman, linux-usb,
	Thomas Winischhofer, Mathias Nyman, Valentina Manea, Shuah Khan,
	Alan Stern, linux-omap, Kukjin Kim, Krzysztof Kozlowski,
	linux-arm-kernel, linux-samsung-soc, Felipe Balbi, Duncan Sands

On Mon, Oct 26, 2020 at 01:47:53PM +0100, Sebastian Andrzej Siewior wrote:
> On 2020-10-25 17:56:47 [+0100], Johan Hovold wrote:
> > There's a ton of issues with this driver, but this is arguably making
> > things worse. A line discipline may call write() from just about any
> > context so we cannot rely on tty being non-NULL here (e.g. PPP).
> 
> I wasn't aware of that. I've been looking at the callers each time a
> `tty' was passed it looked like a preemptible context (due to mutex /
> GFP_KERNEL) and so on.

Yeah, the default line discipline only calls in preemptible context
(these days), but others do not (e.g. see ppp_async_push()).

Johan

^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [PATCH v3 04/13 ] USB: serial: digi_acceleport: Remove in_interrupt() usage
  2020-10-26 14:03     ` [PATCH v3 04/13 ] " Sebastian Andrzej Siewior
@ 2020-10-27  8:26       ` Johan Hovold
  0 siblings, 0 replies; 27+ messages in thread
From: Johan Hovold @ 2020-10-27  8:26 UTC (permalink / raw)
  To: Sebastian Andrzej Siewior
  Cc: Johan Hovold, Thomas Gleixner, LKML, Peter Zijlstra,
	Ahmed S. Darwish, Greg Kroah-Hartman, linux-usb,
	Thomas Winischhofer, Mathias Nyman, Valentina Manea, Shuah Khan,
	Alan Stern, linux-omap, Kukjin Kim, Krzysztof Kozlowski,
	linux-arm-kernel, linux-samsung-soc, Felipe Balbi, Duncan Sands

On Mon, Oct 26, 2020 at 03:03:13PM +0100, Sebastian Andrzej Siewior wrote:
> From: "Ahmed S. Darwish" <a.darwish@linutronix.de>
> 
> The usage of in_interrupt() in drivers is phased out and Linus clearly
> requested that code which changes behaviour depending on context should
> either be separated or the context be conveyed in an argument passed by the
> caller, which usually knows the context.
> 
> The debug printk() in digi_write() prints in_interrupt() as context
> information. This information is imprecisely as it does not distinguish
> between hard-IRQ or disabled botton half and it does consider disabled
> interrupts or preemption. It is not really helpful.

I fixed up a couple of typos and added the missing negation above so
that it reads:

  The debug printk() in digi_write() prints in_interrupt() as context
  information. This information is imprecise as it does not distinguish
  between hard-IRQ or disabled bottom half and it does not consider
  disabled interrupts or preemption. It is not really helpful.
	
> Remove the in_interrupt() printout.
> 
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Cc: Johan Hovold <johan@kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-usb@vger.kernel.org
> ---
> v2…v3:
>   - Don't make dev_dbg() conditional on `tty'
>   - Remove the part "tty happens always in process context" from the
>     commit message. Johan pointed out that for PPP it may happen in
>     bottom half.

Now applied for -next, thanks.

Johan

^ permalink raw reply	[flat|nested] 27+ messages in thread

* Re: [patch V2 06/13] usb: host: isp1362: Replace in_interrupt() usage
  2020-10-19 10:06 ` [patch V2 06/13] usb: host: isp1362: Replace in_interrupt() usage Thomas Gleixner
@ 2020-10-28 11:27   ` Greg Kroah-Hartman
  0 siblings, 0 replies; 27+ messages in thread
From: Greg Kroah-Hartman @ 2020-10-28 11:27 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: LKML, Peter Zijlstra, Ahmed S. Darwish,
	Sebastian Andrzej Siewior, linux-usb, Thomas Winischhofer,
	Johan Hovold, Mathias Nyman, Valentina Manea, Shuah Khan,
	Alan Stern, linux-omap, Kukjin Kim, Krzysztof Kozlowski,
	linux-arm-kernel, linux-samsung-soc, Felipe Balbi, Duncan Sands

On Mon, Oct 19, 2020 at 12:06:35PM +0200, Thomas Gleixner wrote:
> isp1362_show_regs() is a debugging-only function, with no call sites. It
> prints the cached value of the HCuPINTENB register if in_interupt() is
> true, otherwise it reads the actual register content.
> 
> The usage of in_interrupt() in drivers is phased out and Linus clearly
> requested that code which changes behaviour depending on context should
> either be separated or the context be conveyed in an argument passed by the
> caller, which usually knows the context.
> 
> Make the conditional based on a function argument.
> 
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: linux-usb@vger.kernel.org
> ---
> V2: Fix silly typo
> ---
>  drivers/usb/host/isp1362.h |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> --- a/drivers/usb/host/isp1362.h
> +++ b/drivers/usb/host/isp1362.h
> @@ -793,7 +793,8 @@ static void isp1362_write_fifo(struct is
>  			ISP1362_REG_NO(ISP1362_REG_##r), isp1362_read_reg16(d, r));	\
>  }
>  
> -static void __attribute__((__unused__)) isp1362_show_regs(struct isp1362_hcd *isp1362_hcd)
> +static void __attribute__((__unused__))
> +isp1362_show_regs(struct isp1362_hcd *isp1362_hcd, bool cached_inten)
>  {
>  	isp1362_show_reg(isp1362_hcd, HCREVISION);
>  	isp1362_show_reg(isp1362_hcd, HCCONTROL);
> @@ -815,7 +816,7 @@ static void __attribute__((__unused__))
>  	isp1362_show_reg(isp1362_hcd, HCXFERCTR);
>  	isp1362_show_reg(isp1362_hcd, HCuPINT);
>  
> -	if (in_interrupt())
> +	if (cached_inten)
>  		DBG(0, "%-12s[%02x]:     %04x\n", "HCuPINTENB",
>  			 ISP1362_REG_NO(ISP1362_REG_HCuPINTENB), isp1362_hcd->irqenb);
>  	else
> 

Let's just delete this whole function, if no one is calling it, it
should not be present.  I'll go make up a patch for that...

thanks,

greg k-h

^ permalink raw reply	[flat|nested] 27+ messages in thread

end of thread, other threads:[~2020-10-28 22:18 UTC | newest]

Thread overview: 27+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-10-19 10:06 [patch V2 00/13] USB: Cleanup in_interupt/in_irq/in_atomic() usage Thomas Gleixner
2020-10-19 10:06 ` [patch V2 01/13] USB: sisusbvga: Make console support depend on BROKEN Thomas Gleixner
2020-10-19 10:06 ` [patch V2 02/13] USB: serial: keyspan_pda: Replace in_interrupt() usage Thomas Gleixner
2020-10-25 16:56   ` Johan Hovold
2020-10-26 12:47     ` Sebastian Andrzej Siewior
2020-10-27  8:16       ` Johan Hovold
2020-10-19 10:06 ` [patch V2 03/13] USB: serial: keyspan_pda: Consolidate room query Thomas Gleixner
2020-10-25 17:05   ` Johan Hovold
2020-10-19 10:06 ` [patch V2 04/13] USB: serial: digi_acceleport: Remove in_interrupt() usage Thomas Gleixner
2020-10-25 17:16   ` Johan Hovold
2020-10-26 14:03     ` [PATCH v3 04/13 ] " Sebastian Andrzej Siewior
2020-10-27  8:26       ` Johan Hovold
2020-10-19 10:06 ` [patch V2 05/13] usb: xhci: Remove in_interrupt() checks Thomas Gleixner
2020-10-19 10:06 ` [patch V2 06/13] usb: host: isp1362: Replace in_interrupt() usage Thomas Gleixner
2020-10-28 11:27   ` Greg Kroah-Hartman
2020-10-19 10:06 ` [patch V2 07/13] usbip: Remove in_interrupt() check Thomas Gleixner
2020-10-19 10:06 ` [patch V2 08/13] usb: hosts: Remove in_interrupt() from comments Thomas Gleixner
2020-10-19 16:28   ` Alan Stern
2020-10-19 10:06 ` [patch V2 09/13] USB: host: ehci-pmcmsp: Cleanup usb_hcd_msp_remove() Thomas Gleixner
2020-10-19 16:28   ` Alan Stern
2020-10-19 10:06 ` [patch V2 10/13] usb: gadget: pxa27x_udc: Replace in_interrupt() usage in comments Thomas Gleixner
2020-10-19 10:06 ` [patch V2 11/13] usb: gadget: udc: Remove in_interrupt()/in_irq() from comments Thomas Gleixner
2020-10-19 16:28   ` Alan Stern
2020-10-19 10:06 ` [patch V2 12/13] usb: core: Replace in_interrupt() in comments Thomas Gleixner
2020-10-19 16:28   ` Alan Stern
2020-10-19 10:06 ` [patch V2 13/13] usb: atm: Replace in_interrupt() usage in comment Thomas Gleixner
2020-10-19 10:28   ` Duncan Sands

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).