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* [PATCH] Cleanup dependency chain for cros_ec modules
@ 2018-06-04 20:22 Enrico Granata
  2018-06-05  0:06 ` Gwendal Grignou
  0 siblings, 1 reply; 6+ messages in thread
From: Enrico Granata @ 2018-06-04 20:22 UTC (permalink / raw)
  To: LKML; +Cc: gwendal, Enrico Granata, Benson Leung, Olof Johansson, Lee Jones

From: Enrico Granata <egranata@chromium.org>

If one builds the Chrome EC support as modules, there is no explicit
dependency chain amongst the several modules (LPC, CHARDEV, CORE, ...)

This makes it possible - for instance - to rmmod cros_ec_core, even though
cros_ec_dev actively uses it for data transport to the EC chip.

This commit makes two changes in an attempt to address this:
a) moves cros_ec_proto.c as part of the CORE module; this removes the
   possibility of unloading cros_ec_core while cros_ec_dev is using it;
b) enables cros_ec_core to explicitly register a runtime dependency on
   the kernel module that is using its cmd and pkt transfer functions

Signed-off-by: Enrico Granata <egranata@chromium.org>
---

 drivers/mfd/Kconfig                             |  1 -
 drivers/mfd/Makefile                            |  2 +-
 drivers/mfd/cros_ec.c                           | 17 ++++++++++++++++-
 .../{platform/chrome => mfd}/cros_ec_proto.c    |  0
 drivers/platform/chrome/Kconfig                 |  5 -----
 drivers/platform/chrome/Makefile                |  1 -
 drivers/platform/chrome/cros_ec_lpc.c           |  1 +
 include/linux/mfd/cros_ec.h                     |  2 ++
 8 files changed, 20 insertions(+), 9 deletions(-)
 rename drivers/{platform/chrome => mfd}/cros_ec_proto.c (100%)

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index b860eb5aa194..a8daa2072ae6 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -194,7 +194,6 @@ config MFD_CROS_EC
 	tristate "ChromeOS Embedded Controller"
 	select MFD_CORE
 	select CHROME_PLATFORMS
-	select CROS_EC_PROTO
 	depends on X86 || ARM || ARM64 || COMPILE_TEST
 	help
 	  If you say Y here you get support for the ChromeOS Embedded
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index d9d2cf0d32ef..20537bd27695 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -12,7 +12,7 @@ obj-$(CONFIG_MFD_SM501)		+= sm501.o
 obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
 obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
 obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
-cros_ec_core-objs		:= cros_ec.o
+cros_ec_core-objs		:= cros_ec.o cros_ec_proto.o
 cros_ec_core-$(CONFIG_ACPI)	+= cros_ec_acpi_gpe.o
 obj-$(CONFIG_MFD_CROS_EC)	+= cros_ec_core.o
 obj-$(CONFIG_MFD_CROS_EC_I2C)	+= cros_ec_i2c.o
diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
index d61024141e2b..109e9cb1e289 100644
--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -168,9 +168,21 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
 	 */
 	err = cros_ec_sleep_event(ec_dev, 0);
 	if (err < 0)
-		dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
+		dev_dbg(dev, "Error %d clearing sleep event to ec",
 			err);
 
+	if (ec_dev->xfer_fcn_owner != NULL) {
+		err = try_module_get(ec_dev->xfer_fcn_owner);
+		if (err < 0) {
+			dev_err(dev, "Error %d acquiring transfer module", err);
+			return err;
+		}
+		dev_info(dev, "Transfer module %p get successfully",
+			 ec_dev->xfer_fcn_owner);
+	} else {
+		dev_warn(dev, "No transfer module registered");
+	}
+
 	dev_info(dev, "Chrome EC device registered\n");
 
 	cros_ec_acpi_install_gpe_handler(dev);
@@ -193,6 +205,9 @@ int cros_ec_remove(struct cros_ec_device *ec_dev)
 	if (ec_dev->irq)
 		free_irq(ec_dev->irq, ec_dev);
 
+	if (ec_dev->xfer_fcn_owner != NULL)
+		module_put(ec_dev->xfer_fcn_owner);
+
 	return 0;
 }
 EXPORT_SYMBOL(cros_ec_remove);
diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/mfd/cros_ec_proto.c
similarity index 100%
rename from drivers/platform/chrome/cros_ec_proto.c
rename to drivers/mfd/cros_ec_proto.c
diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index e728a96cabfd..a050c9e8b506 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -65,11 +65,6 @@ config CROS_EC_LPC_MEC
 	  If you have a ChromeOS Embedded Controller Microchip EC variant
 	  choose Y here.
 
-config CROS_EC_PROTO
-        bool
-        help
-          ChromeOS EC communication protocol helpers.
-
 config CROS_KBD_LED_BACKLIGHT
 	tristate "Backlight LED support for Chrome OS keyboards"
 	depends on LEDS_CLASS && ACPI
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index ff3b369911f0..0b5e26ca9c96 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -8,5 +8,4 @@ obj-$(CONFIG_CROS_EC_CTL)		+= cros_ec_ctl.o
 cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_reg.o
 cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC)	+= cros_ec_lpc_mec.o
 obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
-obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o
 obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)	+= cros_kbd_led_backlight.o
diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
index 3682e1539251..8f02b188bd3f 100644
--- a/drivers/platform/chrome/cros_ec_lpc.c
+++ b/drivers/platform/chrome/cros_ec_lpc.c
@@ -282,6 +282,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
 	ec_dev->phys_name = dev_name(dev);
 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
+	ec_dev->xfer_fcn_owner = THIS_MODULE;
 	ec_dev->cmd_readmem = cros_ec_lpc_readmem;
 	ec_dev->din_size = sizeof(struct ec_host_response) +
 			   sizeof(struct ec_response_get_protocol_info);
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
index 2d4e23c9ea0a..5239107e5091 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -18,6 +18,7 @@
 
 #include <linux/cdev.h>
 #include <linux/device.h>
+#include <linux/module.h>
 #include <linux/notifier.h>
 #include <linux/mfd/cros_ec_commands.h>
 #include <linux/mutex.h>
@@ -139,6 +140,7 @@ struct cros_ec_device {
 	int dout_size;
 	bool wake_enabled;
 	bool suspended;
+	struct module *xfer_fcn_owner;
 	int (*cmd_xfer)(struct cros_ec_device *ec,
 			struct cros_ec_command *msg);
 	int (*pkt_xfer)(struct cros_ec_device *ec,
-- 
2.17.1.1185.g55be947832-goog

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH] Cleanup dependency chain for cros_ec modules
  2018-06-04 20:22 [PATCH] Cleanup dependency chain for cros_ec modules Enrico Granata
@ 2018-06-05  0:06 ` Gwendal Grignou
  2018-06-05  0:39   ` [PATCH v2] cros_ec: cleanup " Enrico Granata
  2018-06-05  0:43   ` [PATCH v3] " Enrico Granata
  0 siblings, 2 replies; 6+ messages in thread
From: Gwendal Grignou @ 2018-06-05  0:06 UTC (permalink / raw)
  To: Enrico Granata
  Cc: Linux Kernel, egranata, Benson Leung, Olof Johansson, Lee Jones

On Mon, Jun 4, 2018 at 1:22 PM Enrico Granata <egranata@google.com> wrote:
>
> From: Enrico Granata <egranata@chromium.org>
>
> If one builds the Chrome EC support as modules, there is no explicit
> dependency chain amongst the several modules (LPC, CHARDEV, CORE, ...)
>
> This makes it possible - for instance - to rmmod cros_ec_core, even though
> cros_ec_dev actively uses it for data transport to the EC chip.
>
> This commit makes two changes in an attempt to address this:
> a) moves cros_ec_proto.c as part of the CORE module; this removes the
>    possibility of unloading cros_ec_core while cros_ec_dev is using it;
> b) enables cros_ec_core to explicitly register a runtime dependency on
>    the kernel module that is using its cmd and pkt transfer functions
>
> Signed-off-by: Enrico Granata <egranata@chromium.org>
> ---
>
>  drivers/mfd/Kconfig                             |  1 -
>  drivers/mfd/Makefile                            |  2 +-
>  drivers/mfd/cros_ec.c                           | 17 ++++++++++++++++-
>  .../{platform/chrome => mfd}/cros_ec_proto.c    |  0
>  drivers/platform/chrome/Kconfig                 |  5 -----
>  drivers/platform/chrome/Makefile                |  1 -
>  drivers/platform/chrome/cros_ec_lpc.c           |  1 +
>  include/linux/mfd/cros_ec.h                     |  2 ++
>  8 files changed, 20 insertions(+), 9 deletions(-)
>  rename drivers/{platform/chrome => mfd}/cros_ec_proto.c (100%)
>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index b860eb5aa194..a8daa2072ae6 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -194,7 +194,6 @@ config MFD_CROS_EC
>         tristate "ChromeOS Embedded Controller"
>         select MFD_CORE
>         select CHROME_PLATFORMS
> -       select CROS_EC_PROTO
>         depends on X86 || ARM || ARM64 || COMPILE_TEST
>         help
>           If you say Y here you get support for the ChromeOS Embedded
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index d9d2cf0d32ef..20537bd27695 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -12,7 +12,7 @@ obj-$(CONFIG_MFD_SM501)               += sm501.o
>  obj-$(CONFIG_MFD_ASIC3)                += asic3.o tmio_core.o
>  obj-$(CONFIG_MFD_BCM590XX)     += bcm590xx.o
>  obj-$(CONFIG_MFD_BD9571MWV)    += bd9571mwv.o
> -cros_ec_core-objs              := cros_ec.o
> +cros_ec_core-objs              := cros_ec.o cros_ec_proto.o
We try to get cros_ec_proto out of mfd directory, it is weird to
compile something from drivers/platform/chrome/ in drivers/mfd.
>  cros_ec_core-$(CONFIG_ACPI)    += cros_ec_acpi_gpe.o
>  obj-$(CONFIG_MFD_CROS_EC)      += cros_ec_core.o
>  obj-$(CONFIG_MFD_CROS_EC_I2C)  += cros_ec_i2c.o
> diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
> index d61024141e2b..109e9cb1e289 100644
> --- a/drivers/mfd/cros_ec.c
> +++ b/drivers/mfd/cros_ec.c
> @@ -168,9 +168,21 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
>          */
>         err = cros_ec_sleep_event(ec_dev, 0);
>         if (err < 0)
> -               dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
> +               dev_dbg(dev, "Error %d clearing sleep event to ec",
>                         err);
Concatenate both line.
>
> +       if (ec_dev->xfer_fcn_owner != NULL) {
> +               err = try_module_get(ec_dev->xfer_fcn_owner);
> +               if (err < 0) {
> +                       dev_err(dev, "Error %d acquiring transfer module", err);
> +                       return err;
> +               }
> +               dev_info(dev, "Transfer module %p get successfully",
> +                        ec_dev->xfer_fcn_owner);
> +       } else {
> +               dev_warn(dev, "No transfer module registered");
> +       }
> +
>         dev_info(dev, "Chrome EC device registered\n");
>
>         cros_ec_acpi_install_gpe_handler(dev);
> @@ -193,6 +205,9 @@ int cros_ec_remove(struct cros_ec_device *ec_dev)
>         if (ec_dev->irq)
>                 free_irq(ec_dev->irq, ec_dev);
>
> +       if (ec_dev->xfer_fcn_owner != NULL)
> +               module_put(ec_dev->xfer_fcn_owner);
> +
>         return 0;
>  }
>  EXPORT_SYMBOL(cros_ec_remove);
> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/mfd/cros_ec_proto.c
> similarity index 100%
> rename from drivers/platform/chrome/cros_ec_proto.c
> rename to drivers/mfd/cros_ec_proto.c
> diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> index e728a96cabfd..a050c9e8b506 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -65,11 +65,6 @@ config CROS_EC_LPC_MEC
>           If you have a ChromeOS Embedded Controller Microchip EC variant
>           choose Y here.
>
> -config CROS_EC_PROTO
> -        bool
> -        help
> -          ChromeOS EC communication protocol helpers.
> -
>  config CROS_KBD_LED_BACKLIGHT
>         tristate "Backlight LED support for Chrome OS keyboards"
>         depends on LEDS_CLASS && ACPI
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index ff3b369911f0..0b5e26ca9c96 100644
> --- a/drivers/platform/chrome/Makefile
> +++ b/drivers/platform/chrome/Makefile
> @@ -8,5 +8,4 @@ obj-$(CONFIG_CROS_EC_CTL)               += cros_ec_ctl.o
>  cros_ec_lpcs-objs                      := cros_ec_lpc.o cros_ec_lpc_reg.o
>  cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC) += cros_ec_lpc_mec.o
>  obj-$(CONFIG_CROS_EC_LPC)              += cros_ec_lpcs.o
> -obj-$(CONFIG_CROS_EC_PROTO)            += cros_ec_proto.o
>  obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)   += cros_kbd_led_backlight.o
> diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
> index 3682e1539251..8f02b188bd3f 100644
> --- a/drivers/platform/chrome/cros_ec_lpc.c
> +++ b/drivers/platform/chrome/cros_ec_lpc.c
> @@ -282,6 +282,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
>         ec_dev->phys_name = dev_name(dev);
>         ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
>         ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
> +       ec_dev->xfer_fcn_owner = THIS_MODULE;
You need to modify other transport modules as well:
cros_ec_i2c.c, cros_ec_spi.c.
>         ec_dev->cmd_readmem = cros_ec_lpc_readmem;
>         ec_dev->din_size = sizeof(struct ec_host_response) +
>                            sizeof(struct ec_response_get_protocol_info);
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index 2d4e23c9ea0a..5239107e5091 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -18,6 +18,7 @@
>
>  #include <linux/cdev.h>
>  #include <linux/device.h>
> +#include <linux/module.h>
>  #include <linux/notifier.h>
>  #include <linux/mfd/cros_ec_commands.h>
>  #include <linux/mutex.h>
> @@ -139,6 +140,7 @@ struct cros_ec_device {
>         int dout_size;
>         bool wake_enabled;
>         bool suspended;
> +       struct module *xfer_fcn_owner;
Another solution would be to make cros_ec a real module. lpc depends
on cros_ec_register, so lsmod will not unload cros_ec [core functions]
if cros_ec_lpc is still loaded.
>         int (*cmd_xfer)(struct cros_ec_device *ec,
>                         struct cros_ec_command *msg);
>         int (*pkt_xfer)(struct cros_ec_device *ec,
> --
> 2.17.1.1185.g55be947832-goog
>

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH v2] cros_ec: cleanup dependency chain for cros_ec modules
  2018-06-05  0:06 ` Gwendal Grignou
@ 2018-06-05  0:39   ` Enrico Granata
  2018-06-05  0:43   ` [PATCH v3] " Enrico Granata
  1 sibling, 0 replies; 6+ messages in thread
From: Enrico Granata @ 2018-06-05  0:39 UTC (permalink / raw)
  To: linux-kernel; +Cc: egranata, bleung, olof, lee.jones

From: Enrico Granata <egranata@chromium.org>

If one builds the Chrome EC support as modules, there is no explicit
dependency chain amongst the several modules (LPC, CHARDEV, CORE, ...)

This makes it possible - for instance - to rmmod cros_ec_core, even though
cros_ec_dev actively uses it for data transport to the EC chip.

This commit makes two changes in an attempt to address this:
a) moves cros_ec_proto.c as part of the CORE module; this removes the
   possibility of unloading cros_ec_core while cros_ec_dev is using it;
b) enables cros_ec_core to explicitly register a runtime dependency on
   the kernel module that is using its cmd and pkt transfer functions

Series-to: LKML <linux-kernel@vger.kernel.org>
Series-cc: gwendal@google.com
Signed-off-by: Enrico Granata <egranata@chromium.org>
---
 drivers/mfd/Kconfig                             |  1 -
 drivers/mfd/Makefile                            |  2 +-
 drivers/mfd/cros_ec.c                           | 17 ++++++++++++++++-
 .../{platform/chrome => mfd}/cros_ec_proto.c    |  0
 drivers/platform/chrome/Kconfig                 |  5 -----
 drivers/platform/chrome/Makefile                |  1 -
 drivers/platform/chrome/cros_ec_lpc.c           |  1 +
 include/linux/mfd/cros_ec.h                     |  2 ++
 8 files changed, 20 insertions(+), 9 deletions(-)
 rename drivers/{platform/chrome => mfd}/cros_ec_proto.c (100%)

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index b860eb5aa194..a8daa2072ae6 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -194,7 +194,6 @@ config MFD_CROS_EC
 	tristate "ChromeOS Embedded Controller"
 	select MFD_CORE
 	select CHROME_PLATFORMS
-	select CROS_EC_PROTO
 	depends on X86 || ARM || ARM64 || COMPILE_TEST
 	help
 	  If you say Y here you get support for the ChromeOS Embedded
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index d9d2cf0d32ef..20537bd27695 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -12,7 +12,7 @@ obj-$(CONFIG_MFD_SM501)		+= sm501.o
 obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
 obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
 obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
-cros_ec_core-objs		:= cros_ec.o
+cros_ec_core-objs		:= cros_ec.o cros_ec_proto.o
 cros_ec_core-$(CONFIG_ACPI)	+= cros_ec_acpi_gpe.o
 obj-$(CONFIG_MFD_CROS_EC)	+= cros_ec_core.o
 obj-$(CONFIG_MFD_CROS_EC_I2C)	+= cros_ec_i2c.o
diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
index d61024141e2b..109e9cb1e289 100644
--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -168,9 +168,21 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
 	 */
 	err = cros_ec_sleep_event(ec_dev, 0);
 	if (err < 0)
-		dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
+		dev_dbg(dev, "Error %d clearing sleep event to ec",
 			err);
 
+	if (ec_dev->xfer_fcn_owner != NULL) {
+		err = try_module_get(ec_dev->xfer_fcn_owner);
+		if (err < 0) {
+			dev_err(dev, "Error %d acquiring transfer module", err);
+			return err;
+		}
+		dev_info(dev, "Transfer module %p get successfully",
+			 ec_dev->xfer_fcn_owner);
+	} else {
+		dev_warn(dev, "No transfer module registered");
+	}
+
 	dev_info(dev, "Chrome EC device registered\n");
 
 	cros_ec_acpi_install_gpe_handler(dev);
@@ -193,6 +205,9 @@ int cros_ec_remove(struct cros_ec_device *ec_dev)
 	if (ec_dev->irq)
 		free_irq(ec_dev->irq, ec_dev);
 
+	if (ec_dev->xfer_fcn_owner != NULL)
+		module_put(ec_dev->xfer_fcn_owner);
+
 	return 0;
 }
 EXPORT_SYMBOL(cros_ec_remove);
diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/mfd/cros_ec_proto.c
similarity index 100%
rename from drivers/platform/chrome/cros_ec_proto.c
rename to drivers/mfd/cros_ec_proto.c
diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index e728a96cabfd..a050c9e8b506 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -65,11 +65,6 @@ config CROS_EC_LPC_MEC
 	  If you have a ChromeOS Embedded Controller Microchip EC variant
 	  choose Y here.
 
-config CROS_EC_PROTO
-        bool
-        help
-          ChromeOS EC communication protocol helpers.
-
 config CROS_KBD_LED_BACKLIGHT
 	tristate "Backlight LED support for Chrome OS keyboards"
 	depends on LEDS_CLASS && ACPI
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index ff3b369911f0..0b5e26ca9c96 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -8,5 +8,4 @@ obj-$(CONFIG_CROS_EC_CTL)		+= cros_ec_ctl.o
 cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_reg.o
 cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC)	+= cros_ec_lpc_mec.o
 obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
-obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o
 obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)	+= cros_kbd_led_backlight.o
diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
index 3682e1539251..8f02b188bd3f 100644
--- a/drivers/platform/chrome/cros_ec_lpc.c
+++ b/drivers/platform/chrome/cros_ec_lpc.c
@@ -282,6 +282,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
 	ec_dev->phys_name = dev_name(dev);
 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
+	ec_dev->xfer_fcn_owner = THIS_MODULE;
 	ec_dev->cmd_readmem = cros_ec_lpc_readmem;
 	ec_dev->din_size = sizeof(struct ec_host_response) +
 			   sizeof(struct ec_response_get_protocol_info);
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
index 2d4e23c9ea0a..5239107e5091 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -18,6 +18,7 @@
 
 #include <linux/cdev.h>
 #include <linux/device.h>
+#include <linux/module.h>
 #include <linux/notifier.h>
 #include <linux/mfd/cros_ec_commands.h>
 #include <linux/mutex.h>
@@ -139,6 +140,7 @@ struct cros_ec_device {
 	int dout_size;
 	bool wake_enabled;
 	bool suspended;
+	struct module *xfer_fcn_owner;
 	int (*cmd_xfer)(struct cros_ec_device *ec,
 			struct cros_ec_command *msg);
 	int (*pkt_xfer)(struct cros_ec_device *ec,
-- 
2.17.1.1185.g55be947832-goog

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH v3] cros_ec: cleanup dependency chain for cros_ec modules
  2018-06-05  0:06 ` Gwendal Grignou
  2018-06-05  0:39   ` [PATCH v2] cros_ec: cleanup " Enrico Granata
@ 2018-06-05  0:43   ` Enrico Granata
  2018-06-18  6:35     ` Lee Jones
  1 sibling, 1 reply; 6+ messages in thread
From: Enrico Granata @ 2018-06-05  0:43 UTC (permalink / raw)
  To: linux-kernel; +Cc: egranata, bleung, olof, lee.jones, gwendal

From: Enrico Granata <egranata@chromium.org>

If one builds the Chrome EC support as modules, there is no explicit
dependency chain amongst the several modules (LPC, CHARDEV, CORE, ...)

This makes it possible - for instance - to rmmod cros_ec_core, even though
cros_ec_dev actively uses it for data transport to the EC chip.

This commit makes two changes in an attempt to address this:
a) moves cros_ec_proto.c as part of the CORE module; this removes the
   possibility of unloading cros_ec_core while cros_ec_dev is using it;
b) enables cros_ec_core to explicitly register a runtime dependency on
   the kernel module that is using its cmd and pkt transfer functions

Series-to: LKML <linux-kernel@vger.kernel.org>
Series-cc: gwendal@google.com
Signed-off-by: Enrico Granata <egranata@chromium.org>
---
 drivers/mfd/Kconfig                              |  1 -
 drivers/mfd/Makefile                             |  2 +-
 drivers/mfd/cros_ec.c                            | 18 ++++++++++++++++--
 drivers/mfd/cros_ec_i2c.c                        |  1 +
 drivers/{platform/chrome => mfd}/cros_ec_proto.c |  0
 drivers/mfd/cros_ec_spi.c                        |  1 +
 drivers/platform/chrome/Kconfig                  |  5 -----
 drivers/platform/chrome/Makefile                 |  1 -
 drivers/platform/chrome/cros_ec_lpc.c            |  1 +
 include/linux/mfd/cros_ec.h                      |  2 ++
 10 files changed, 22 insertions(+), 10 deletions(-)
 rename drivers/{platform/chrome => mfd}/cros_ec_proto.c (100%)

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index b860eb5aa194..a8daa2072ae6 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -194,7 +194,6 @@ config MFD_CROS_EC
 	tristate "ChromeOS Embedded Controller"
 	select MFD_CORE
 	select CHROME_PLATFORMS
-	select CROS_EC_PROTO
 	depends on X86 || ARM || ARM64 || COMPILE_TEST
 	help
 	  If you say Y here you get support for the ChromeOS Embedded
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index d9d2cf0d32ef..20537bd27695 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -12,7 +12,7 @@ obj-$(CONFIG_MFD_SM501)		+= sm501.o
 obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
 obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
 obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
-cros_ec_core-objs		:= cros_ec.o
+cros_ec_core-objs		:= cros_ec.o cros_ec_proto.o
 cros_ec_core-$(CONFIG_ACPI)	+= cros_ec_acpi_gpe.o
 obj-$(CONFIG_MFD_CROS_EC)	+= cros_ec_core.o
 obj-$(CONFIG_MFD_CROS_EC_I2C)	+= cros_ec_i2c.o
diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
index d61024141e2b..9660dc0fc079 100644
--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -168,8 +168,19 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
 	 */
 	err = cros_ec_sleep_event(ec_dev, 0);
 	if (err < 0)
-		dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
-			err);
+		dev_dbg(dev, "Error %d clearing sleep event to ec", err);
+
+	if (ec_dev->xfer_fcn_owner != NULL) {
+		err = try_module_get(ec_dev->xfer_fcn_owner);
+		if (err < 0) {
+			dev_err(dev, "Error %d acquiring transfer module", err);
+			return err;
+		}
+		dev_info(dev, "Transfer module %p get successfully",
+			 ec_dev->xfer_fcn_owner);
+	} else {
+		dev_warn(dev, "No transfer module registered");
+	}
 
 	dev_info(dev, "Chrome EC device registered\n");
 
@@ -193,6 +204,9 @@ int cros_ec_remove(struct cros_ec_device *ec_dev)
 	if (ec_dev->irq)
 		free_irq(ec_dev->irq, ec_dev);
 
+	if (ec_dev->xfer_fcn_owner != NULL)
+		module_put(ec_dev->xfer_fcn_owner);
+
 	return 0;
 }
 EXPORT_SYMBOL(cros_ec_remove);
diff --git a/drivers/mfd/cros_ec_i2c.c b/drivers/mfd/cros_ec_i2c.c
index 9f70de1e4c70..72b0473eb868 100644
--- a/drivers/mfd/cros_ec_i2c.c
+++ b/drivers/mfd/cros_ec_i2c.c
@@ -302,6 +302,7 @@ static int cros_ec_i2c_probe(struct i2c_client *client,
 	ec_dev->irq = client->irq;
 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
+	ec_dev->xfer_fcn_owner = THIS_MODULE;
 	ec_dev->phys_name = client->adapter->name;
 	ec_dev->din_size = sizeof(struct ec_host_response_i2c) +
 			   sizeof(struct ec_response_get_protocol_info);
diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/mfd/cros_ec_proto.c
similarity index 100%
rename from drivers/platform/chrome/cros_ec_proto.c
rename to drivers/mfd/cros_ec_proto.c
diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
index 2060d1483043..ce2849790b95 100644
--- a/drivers/mfd/cros_ec_spi.c
+++ b/drivers/mfd/cros_ec_spi.c
@@ -666,6 +666,7 @@ static int cros_ec_spi_probe(struct spi_device *spi)
 	ec_dev->irq = spi->irq;
 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi;
 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_spi;
+	ec_dev->xfer_fcn_owner = THIS_MODULE;
 	ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
 	ec_dev->din_size = EC_MSG_PREAMBLE_COUNT +
 			   sizeof(struct ec_host_response) +
diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index e728a96cabfd..a050c9e8b506 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -65,11 +65,6 @@ config CROS_EC_LPC_MEC
 	  If you have a ChromeOS Embedded Controller Microchip EC variant
 	  choose Y here.
 
-config CROS_EC_PROTO
-        bool
-        help
-          ChromeOS EC communication protocol helpers.
-
 config CROS_KBD_LED_BACKLIGHT
 	tristate "Backlight LED support for Chrome OS keyboards"
 	depends on LEDS_CLASS && ACPI
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index ff3b369911f0..0b5e26ca9c96 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -8,5 +8,4 @@ obj-$(CONFIG_CROS_EC_CTL)		+= cros_ec_ctl.o
 cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_reg.o
 cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC)	+= cros_ec_lpc_mec.o
 obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
-obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o
 obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)	+= cros_kbd_led_backlight.o
diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
index 3682e1539251..8f02b188bd3f 100644
--- a/drivers/platform/chrome/cros_ec_lpc.c
+++ b/drivers/platform/chrome/cros_ec_lpc.c
@@ -282,6 +282,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
 	ec_dev->phys_name = dev_name(dev);
 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
+	ec_dev->xfer_fcn_owner = THIS_MODULE;
 	ec_dev->cmd_readmem = cros_ec_lpc_readmem;
 	ec_dev->din_size = sizeof(struct ec_host_response) +
 			   sizeof(struct ec_response_get_protocol_info);
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
index 2d4e23c9ea0a..5239107e5091 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -18,6 +18,7 @@
 
 #include <linux/cdev.h>
 #include <linux/device.h>
+#include <linux/module.h>
 #include <linux/notifier.h>
 #include <linux/mfd/cros_ec_commands.h>
 #include <linux/mutex.h>
@@ -139,6 +140,7 @@ struct cros_ec_device {
 	int dout_size;
 	bool wake_enabled;
 	bool suspended;
+	struct module *xfer_fcn_owner;
 	int (*cmd_xfer)(struct cros_ec_device *ec,
 			struct cros_ec_command *msg);
 	int (*pkt_xfer)(struct cros_ec_device *ec,
-- 
2.17.1.1185.g55be947832-goog

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH v3] cros_ec: cleanup dependency chain for cros_ec modules
  2018-06-05  0:43   ` [PATCH v3] " Enrico Granata
@ 2018-06-18  6:35     ` Lee Jones
  2018-06-20 20:57       ` Dmitry Torokhov
  0 siblings, 1 reply; 6+ messages in thread
From: Lee Jones @ 2018-06-18  6:35 UTC (permalink / raw)
  To: Enrico Granata; +Cc: linux-kernel, egranata, bleung, olof, gwendal

On Mon, 04 Jun 2018, Enrico Granata wrote:

> From: Enrico Granata <egranata@chromium.org>
> 
> If one builds the Chrome EC support as modules, there is no explicit
> dependency chain amongst the several modules (LPC, CHARDEV, CORE, ...)
> 
> This makes it possible - for instance - to rmmod cros_ec_core, even though
> cros_ec_dev actively uses it for data transport to the EC chip.
> 
> This commit makes two changes in an attempt to address this:
> a) moves cros_ec_proto.c as part of the CORE module; this removes the
>    possibility of unloading cros_ec_core while cros_ec_dev is using it;
> b) enables cros_ec_core to explicitly register a runtime dependency on
>    the kernel module that is using its cmd and pkt transfer functions
> 
> Series-to: LKML <linux-kernel@vger.kernel.org>
> Series-cc: gwendal@google.com
> Signed-off-by: Enrico Granata <egranata@chromium.org>
> ---
>  drivers/mfd/Kconfig                              |  1 -
>  drivers/mfd/Makefile                             |  2 +-
>  drivers/mfd/cros_ec.c                            | 18 ++++++++++++++++--
>  drivers/mfd/cros_ec_i2c.c                        |  1 +
>  drivers/{platform/chrome => mfd}/cros_ec_proto.c |  0
>  drivers/mfd/cros_ec_spi.c                        |  1 +
>  drivers/platform/chrome/Kconfig                  |  5 -----
>  drivers/platform/chrome/Makefile                 |  1 -
>  drivers/platform/chrome/cros_ec_lpc.c            |  1 +
>  include/linux/mfd/cros_ec.h                      |  2 ++
>  10 files changed, 22 insertions(+), 10 deletions(-)
>  rename drivers/{platform/chrome => mfd}/cros_ec_proto.c (100%)
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index b860eb5aa194..a8daa2072ae6 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -194,7 +194,6 @@ config MFD_CROS_EC
>  	tristate "ChromeOS Embedded Controller"
>  	select MFD_CORE
>  	select CHROME_PLATFORMS
> -	select CROS_EC_PROTO
>  	depends on X86 || ARM || ARM64 || COMPILE_TEST
>  	help
>  	  If you say Y here you get support for the ChromeOS Embedded
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index d9d2cf0d32ef..20537bd27695 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -12,7 +12,7 @@ obj-$(CONFIG_MFD_SM501)		+= sm501.o
>  obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
>  obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
>  obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
> -cros_ec_core-objs		:= cros_ec.o
> +cros_ec_core-objs		:= cros_ec.o cros_ec_proto.o
>  cros_ec_core-$(CONFIG_ACPI)	+= cros_ec_acpi_gpe.o
>  obj-$(CONFIG_MFD_CROS_EC)	+= cros_ec_core.o
>  obj-$(CONFIG_MFD_CROS_EC_I2C)	+= cros_ec_i2c.o
> diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
> index d61024141e2b..9660dc0fc079 100644
> --- a/drivers/mfd/cros_ec.c
> +++ b/drivers/mfd/cros_ec.c
> @@ -168,8 +168,19 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
>  	 */
>  	err = cros_ec_sleep_event(ec_dev, 0);
>  	if (err < 0)
> -		dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
> -			err);
> +		dev_dbg(dev, "Error %d clearing sleep event to ec", err);

This change is unrelated to the patch.

> +	if (ec_dev->xfer_fcn_owner != NULL) {

if (ec_dev->xfer_fcn_owner) ?

> +		err = try_module_get(ec_dev->xfer_fcn_owner);
> +		if (err < 0) {

This logic is wrong.  try_module_get() returns a bool.

> +			dev_err(dev, "Error %d acquiring transfer module", err);
> +			return err;
> +		}
> +		dev_info(dev, "Transfer module %p get successfully",
> +			 ec_dev->xfer_fcn_owner);
> +	} else {
> +		dev_warn(dev, "No transfer module registered");
> +	}
>  
>  	dev_info(dev, "Chrome EC device registered\n");
>  
> @@ -193,6 +204,9 @@ int cros_ec_remove(struct cros_ec_device *ec_dev)
>  	if (ec_dev->irq)
>  		free_irq(ec_dev->irq, ec_dev);
>  
> +	if (ec_dev->xfer_fcn_owner != NULL)

As above.

> +		module_put(ec_dev->xfer_fcn_owner);
> +
>  	return 0;
>  }
>  EXPORT_SYMBOL(cros_ec_remove);
> diff --git a/drivers/mfd/cros_ec_i2c.c b/drivers/mfd/cros_ec_i2c.c
> index 9f70de1e4c70..72b0473eb868 100644
> --- a/drivers/mfd/cros_ec_i2c.c
> +++ b/drivers/mfd/cros_ec_i2c.c
> @@ -302,6 +302,7 @@ static int cros_ec_i2c_probe(struct i2c_client *client,
>  	ec_dev->irq = client->irq;
>  	ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
>  	ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
> +	ec_dev->xfer_fcn_owner = THIS_MODULE;
>  	ec_dev->phys_name = client->adapter->name;
>  	ec_dev->din_size = sizeof(struct ec_host_response_i2c) +
>  			   sizeof(struct ec_response_get_protocol_info);
> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/mfd/cros_ec_proto.c
> similarity index 100%
> rename from drivers/platform/chrome/cros_ec_proto.c
> rename to drivers/mfd/cros_ec_proto.c
> diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
> index 2060d1483043..ce2849790b95 100644
> --- a/drivers/mfd/cros_ec_spi.c
> +++ b/drivers/mfd/cros_ec_spi.c
> @@ -666,6 +666,7 @@ static int cros_ec_spi_probe(struct spi_device *spi)
>  	ec_dev->irq = spi->irq;
>  	ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi;
>  	ec_dev->pkt_xfer = cros_ec_pkt_xfer_spi;
> +	ec_dev->xfer_fcn_owner = THIS_MODULE;
>  	ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
>  	ec_dev->din_size = EC_MSG_PREAMBLE_COUNT +
>  			   sizeof(struct ec_host_response) +
> diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> index e728a96cabfd..a050c9e8b506 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -65,11 +65,6 @@ config CROS_EC_LPC_MEC
>  	  If you have a ChromeOS Embedded Controller Microchip EC variant
>  	  choose Y here.
>  
> -config CROS_EC_PROTO
> -        bool
> -        help
> -          ChromeOS EC communication protocol helpers.
> -
>  config CROS_KBD_LED_BACKLIGHT
>  	tristate "Backlight LED support for Chrome OS keyboards"
>  	depends on LEDS_CLASS && ACPI
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index ff3b369911f0..0b5e26ca9c96 100644
> --- a/drivers/platform/chrome/Makefile
> +++ b/drivers/platform/chrome/Makefile
> @@ -8,5 +8,4 @@ obj-$(CONFIG_CROS_EC_CTL)		+= cros_ec_ctl.o
>  cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_reg.o
>  cros_ec_lpcs-$(CONFIG_CROS_EC_LPC_MEC)	+= cros_ec_lpc_mec.o
>  obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
> -obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o
>  obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)	+= cros_kbd_led_backlight.o
> diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
> index 3682e1539251..8f02b188bd3f 100644
> --- a/drivers/platform/chrome/cros_ec_lpc.c
> +++ b/drivers/platform/chrome/cros_ec_lpc.c
> @@ -282,6 +282,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
>  	ec_dev->phys_name = dev_name(dev);
>  	ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
>  	ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
> +	ec_dev->xfer_fcn_owner = THIS_MODULE;
>  	ec_dev->cmd_readmem = cros_ec_lpc_readmem;
>  	ec_dev->din_size = sizeof(struct ec_host_response) +
>  			   sizeof(struct ec_response_get_protocol_info);
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index 2d4e23c9ea0a..5239107e5091 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -18,6 +18,7 @@
>  
>  #include <linux/cdev.h>
>  #include <linux/device.h>
> +#include <linux/module.h>
>  #include <linux/notifier.h>
>  #include <linux/mfd/cros_ec_commands.h>
>  #include <linux/mutex.h>
> @@ -139,6 +140,7 @@ struct cros_ec_device {
>  	int dout_size;
>  	bool wake_enabled;
>  	bool suspended;
> +	struct module *xfer_fcn_owner;

Why do you have to introduce a new property?

Can't you just use THIS_MODULE in try_module_get()?

>  	int (*cmd_xfer)(struct cros_ec_device *ec,
>  			struct cros_ec_command *msg);
>  	int (*pkt_xfer)(struct cros_ec_device *ec,

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH v3] cros_ec: cleanup dependency chain for cros_ec modules
  2018-06-18  6:35     ` Lee Jones
@ 2018-06-20 20:57       ` Dmitry Torokhov
  0 siblings, 0 replies; 6+ messages in thread
From: Dmitry Torokhov @ 2018-06-20 20:57 UTC (permalink / raw)
  To: Lee Jones, egranata
  Cc: lkml, egranata, Benson Leung, Olof Johansson, Gwendal Grignou

On Sun, Jun 17, 2018 at 11:37 PM Lee Jones <lee.jones@linaro.org> wrote:
>
> On Mon, 04 Jun 2018, Enrico Granata wrote:
>
> > From: Enrico Granata <egranata@chromium.org>
> >
> > If one builds the Chrome EC support as modules, there is no explicit
> > dependency chain amongst the several modules (LPC, CHARDEV, CORE, ...)
> >
> > This makes it possible - for instance - to rmmod cros_ec_core, even though
> > cros_ec_dev actively uses it for data transport to the EC chip.
> >
> > This commit makes two changes in an attempt to address this:
> > a) moves cros_ec_proto.c as part of the CORE module; this removes the
> >    possibility of unloading cros_ec_core while cros_ec_dev is using it;
> > b) enables cros_ec_core to explicitly register a runtime dependency on
> >    the kernel module that is using its cmd and pkt transfer functions
> >
> > Series-to: LKML <linux-kernel@vger.kernel.org>
> > Series-cc: gwendal@google.com
> > Signed-off-by: Enrico Granata <egranata@chromium.org>
> > ---
> >  drivers/mfd/Kconfig                              |  1 -
> >  drivers/mfd/Makefile                             |  2 +-
> >  drivers/mfd/cros_ec.c                            | 18 ++++++++++++++++--
> >  drivers/mfd/cros_ec_i2c.c                        |  1 +
> >  drivers/{platform/chrome => mfd}/cros_ec_proto.c |  0
> >  drivers/mfd/cros_ec_spi.c                        |  1 +
> >  drivers/platform/chrome/Kconfig                  |  5 -----
> >  drivers/platform/chrome/Makefile                 |  1 -
> >  drivers/platform/chrome/cros_ec_lpc.c            |  1 +
> >  include/linux/mfd/cros_ec.h                      |  2 ++
> >  10 files changed, 22 insertions(+), 10 deletions(-)
> >  rename drivers/{platform/chrome => mfd}/cros_ec_proto.c (100%)
> >
> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > index b860eb5aa194..a8daa2072ae6 100644
> > --- a/drivers/mfd/Kconfig
> > +++ b/drivers/mfd/Kconfig
> > @@ -194,7 +194,6 @@ config MFD_CROS_EC
> >       tristate "ChromeOS Embedded Controller"
> >       select MFD_CORE
> >       select CHROME_PLATFORMS
> > -     select CROS_EC_PROTO
> >       depends on X86 || ARM || ARM64 || COMPILE_TEST
> >       help
> >         If you say Y here you get support for the ChromeOS Embedded
> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > index d9d2cf0d32ef..20537bd27695 100644
> > --- a/drivers/mfd/Makefile
> > +++ b/drivers/mfd/Makefile
> > @@ -12,7 +12,7 @@ obj-$(CONFIG_MFD_SM501)             += sm501.o
> >  obj-$(CONFIG_MFD_ASIC3)              += asic3.o tmio_core.o
> >  obj-$(CONFIG_MFD_BCM590XX)   += bcm590xx.o
> >  obj-$(CONFIG_MFD_BD9571MWV)  += bd9571mwv.o
> > -cros_ec_core-objs            := cros_ec.o
> > +cros_ec_core-objs            := cros_ec.o cros_ec_proto.o
> >  cros_ec_core-$(CONFIG_ACPI)  += cros_ec_acpi_gpe.o
> >  obj-$(CONFIG_MFD_CROS_EC)    += cros_ec_core.o
> >  obj-$(CONFIG_MFD_CROS_EC_I2C)        += cros_ec_i2c.o
> > diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
> > index d61024141e2b..9660dc0fc079 100644
> > --- a/drivers/mfd/cros_ec.c
> > +++ b/drivers/mfd/cros_ec.c
> > @@ -168,8 +168,19 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
> >        */
> >       err = cros_ec_sleep_event(ec_dev, 0);
> >       if (err < 0)
> > -             dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
> > -                     err);
> > +             dev_dbg(dev, "Error %d clearing sleep event to ec", err);
>
> This change is unrelated to the patch.
>
> > +     if (ec_dev->xfer_fcn_owner != NULL) {
>
> if (ec_dev->xfer_fcn_owner) ?
>
> > +             err = try_module_get(ec_dev->xfer_fcn_owner);
> > +             if (err < 0) {
>
> This logic is wrong.  try_module_get() returns a bool.

I do not think this is needed at all: the transport drivers (i2c, api)
are using cros_ec_register() provided by cros_ec core, which should
bump up refcount on cros_ec core module preventing it from unloading.
And unloading transport driver should unregister EC instance, stopping
IO.

If cros_ec_dev is not prepared to handle "dead" devices - it is issue
for cros_ec_dev to solve. By the way, it is not solvable my
disallowing module unloading: one can always tear down a device by
manually unbinding driver via sysfs.

Thanks.

-- 
Dmitry

^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2018-06-20 20:58 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-06-04 20:22 [PATCH] Cleanup dependency chain for cros_ec modules Enrico Granata
2018-06-05  0:06 ` Gwendal Grignou
2018-06-05  0:39   ` [PATCH v2] cros_ec: cleanup " Enrico Granata
2018-06-05  0:43   ` [PATCH v3] " Enrico Granata
2018-06-18  6:35     ` Lee Jones
2018-06-20 20:57       ` Dmitry Torokhov

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