[PATCH RESEND net-next v2 0/4] WWAN debugfs tweaks

[PATCH RESEND net-next v2 0/4] WWAN debugfs tweaks

[Sergey Ryazanov]

Resent after dependency [2] was merged to the net-next tree. Added
Leon's reviewed-by tag from the first V2 submission.

This is a follow-up series to just applied IOSM (and WWAN) debugfs
interface support [1]. The series has two main goals:
1. move the driver-specific debugfs knobs to a subdirectory;
2. make the debugfs interface optional for both IOSM and for the WWAN
   core.

As for the first part, I must say that it was my mistake. I suggested to
place debugfs entries under a common per WWAN device directory. But I
missed the driver subdirectory in the example, so it become:

/sys/kernel/debugfs/wwan/wwan0/trace

Since the traces collection is a driver-specific feature, it is better
to keep it under the driver-specific subdirectory:

/sys/kernel/debugfs/wwan/wwan0/iosm/trace

It is desirable to be able to entirely disable the debugfs interface. It
can be disabled for several reasons, including security and consumed
storage space. See detailed rationale with usage example in the 4th
patch.

The changes themselves are relatively simple, but require a code
rearrangement. So to make changes clear, I chose to split them into
preparatory and main changes and properly describe each of them.

IOSM part is compile-tested only since I do not have IOSM supported
device, so it needs Ack from the driver developers.

I would like to thank Johannes Berg and Leon Romanovsky. Their
suggestions and comments helped a lot to rework the initial
over-engineered solution to something less confusing and much more
simple. Thanks!

Changes since v1:
* 1st and 2nd patches were not changed
* add missed field description in the 3rd patch
* 4th and 5th patches have been merged into a single one with rework of
  the configuration options and and a few other fixes (see detailed
  changelog in the patch)

1. https://lore.kernel.org/netdev/20211120162155.1216081-1-m.chetan.kumar@linux.intel.com
2. https://patchwork.kernel.org/project/netdevbpf/patch/20211204174033.950528-1-arnd@kernel.org/

Cc: M Chetan Kumar <m.chetan.kumar@intel.com>
Cc: Intel Corporation <linuxwwan@intel.com>
Cc: Loic Poulain <loic.poulain@linaro.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Leon Romanovsky <leon@kernel.org>

Sergey Ryazanov (4):
  net: wwan: iosm: consolidate trace port init code
  net: wwan: iosm: allow trace port be uninitialized
  net: wwan: iosm: move debugfs knobs into a subdir
  net: wwan: make debugfs optional

 drivers/net/wwan/Kconfig                  | 13 +++++++++-
 drivers/net/wwan/iosm/Makefile            |  5 +++-
 drivers/net/wwan/iosm/iosm_ipc_debugfs.c  | 29 +++++++++++++++++++++++
 drivers/net/wwan/iosm/iosm_ipc_debugfs.h  | 17 +++++++++++++
 drivers/net/wwan/iosm/iosm_ipc_imem.c     | 13 ++++------
 drivers/net/wwan/iosm/iosm_ipc_imem.h     |  6 +++++
 drivers/net/wwan/iosm/iosm_ipc_imem_ops.c | 18 --------------
 drivers/net/wwan/iosm/iosm_ipc_imem_ops.h |  2 +-
 drivers/net/wwan/iosm/iosm_ipc_trace.c    | 23 ++++++++++++------
 drivers/net/wwan/iosm/iosm_ipc_trace.h    | 25 ++++++++++++++++++-
 drivers/net/wwan/wwan_core.c              | 17 +++++++++----
 include/linux/wwan.h                      |  7 ++++++
 12 files changed, 134 insertions(+), 41 deletions(-)
 create mode 100644 drivers/net/wwan/iosm/iosm_ipc_debugfs.c
 create mode 100644 drivers/net/wwan/iosm/iosm_ipc_debugfs.h

-- 
2.32.0

[PATCH RESEND net-next v2 1/4] net: wwan: iosm: consolidate trace port init code

[Sergey Ryazanov]

Move the channel related structures initialization from
ipc_imem_channel_init() to ipc_trace_init() and call it directly. On the
one hand, this makes the trace port initialization symmetric to the
deitialization, that is, it removes the additional wrapper.

On the other hand, this change consolidates the trace port related code
into a single source file, what facilitates an upcoming disabling of
this functionality by a user choise.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
---
Changes since v1:
* no changes

 drivers/net/wwan/iosm/iosm_ipc_imem.c     |  2 +-
 drivers/net/wwan/iosm/iosm_ipc_imem_ops.c | 18 ------------------
 drivers/net/wwan/iosm/iosm_ipc_imem_ops.h |  2 +-
 drivers/net/wwan/iosm/iosm_ipc_trace.c    |  8 +++++++-
 4 files changed, 9 insertions(+), 21 deletions(-)

diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem.c b/drivers/net/wwan/iosm/iosm_ipc_imem.c
index 1be07114c85d..49bdadb855e5 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem.c
@@ -554,7 +554,7 @@ static void ipc_imem_run_state_worker(struct work_struct *instance)
 		ctrl_chl_idx++;
 	}
 
-	ipc_imem->trace = ipc_imem_trace_channel_init(ipc_imem);
+	ipc_imem->trace = ipc_trace_init(ipc_imem);
 	if (!ipc_imem->trace) {
 		dev_err(ipc_imem->dev, "trace channel init failed");
 		return;
diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c b/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c
index 43f1796a8984..d2072a84ab08 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem_ops.c
@@ -11,7 +11,6 @@
 #include "iosm_ipc_imem_ops.h"
 #include "iosm_ipc_port.h"
 #include "iosm_ipc_task_queue.h"
-#include "iosm_ipc_trace.h"
 
 /* Open a packet data online channel between the network layer and CP. */
 int ipc_imem_sys_wwan_open(struct iosm_imem *ipc_imem, int if_id)
@@ -108,23 +107,6 @@ void ipc_imem_wwan_channel_init(struct iosm_imem *ipc_imem,
 			"failed to register the ipc_wwan interfaces");
 }
 
-/**
- * ipc_imem_trace_channel_init - Initializes trace channel.
- * @ipc_imem:          Pointer to iosm_imem struct.
- *
- * Returns: Pointer to trace instance on success else NULL
- */
-struct iosm_trace *ipc_imem_trace_channel_init(struct iosm_imem *ipc_imem)
-{
-	struct ipc_chnl_cfg chnl_cfg = { 0 };
-
-	ipc_chnl_cfg_get(&chnl_cfg, IPC_MEM_CTRL_CHL_ID_3);
-	ipc_imem_channel_init(ipc_imem, IPC_CTYPE_CTRL, chnl_cfg,
-			      IRQ_MOD_OFF);
-
-	return ipc_trace_init(ipc_imem);
-}
-
 /* Map SKB to DMA for transfer */
 static int ipc_imem_map_skb_to_dma(struct iosm_imem *ipc_imem,
 				   struct sk_buff *skb)
diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem_ops.h b/drivers/net/wwan/iosm/iosm_ipc_imem_ops.h
index e36ee2782629..f8afb217d9e2 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem_ops.h
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem_ops.h
@@ -141,5 +141,5 @@ int ipc_imem_sys_devlink_read(struct iosm_devlink *ipc_devlink, u8 *data,
  */
 int ipc_imem_sys_devlink_write(struct iosm_devlink *ipc_devlink,
 			       unsigned char *buf, int count);
-struct iosm_trace *ipc_imem_trace_channel_init(struct iosm_imem *ipc_imem);
+
 #endif
diff --git a/drivers/net/wwan/iosm/iosm_ipc_trace.c b/drivers/net/wwan/iosm/iosm_ipc_trace.c
index c5fa12599c2b..5f5cfd39bede 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_trace.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_trace.c
@@ -132,9 +132,15 @@ static const struct file_operations ipc_trace_fops = {
  */
 struct iosm_trace *ipc_trace_init(struct iosm_imem *ipc_imem)
 {
-	struct iosm_trace *ipc_trace = kzalloc(sizeof(*ipc_trace), GFP_KERNEL);
+	struct ipc_chnl_cfg chnl_cfg = { 0 };
+	struct iosm_trace *ipc_trace;
 	struct dentry *debugfs_pdev;
 
+	ipc_chnl_cfg_get(&chnl_cfg, IPC_MEM_CTRL_CHL_ID_3);
+	ipc_imem_channel_init(ipc_imem, IPC_CTYPE_CTRL, chnl_cfg,
+			      IRQ_MOD_OFF);
+
+	ipc_trace = kzalloc(sizeof(*ipc_trace), GFP_KERNEL);
 	if (!ipc_trace)
 		return NULL;
 
-- 
2.32.0

[PATCH RESEND net-next v2 2/4] net: wwan: iosm: allow trace port be uninitialized

[Sergey Ryazanov]

Collecting modem firmware traces is optional for the regular modem use.
There are not many reasons for aborting device initialization due to an
inability to initialize the trace port and (or) its debugfs interface.
So, demote the initialization failure erro message into a warning and do
not break the initialization sequence in this case. Rework packet
processing and deinitialization so that they do not crash in case of
uninitialized trace port.

This change is mainly a preparation for an upcoming configuration option
introduction that will help disable driver debugfs functionality.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
---
Changes since v1:
* no changes

 drivers/net/wwan/iosm/iosm_ipc_imem.c  | 8 +++-----
 drivers/net/wwan/iosm/iosm_ipc_trace.c | 3 +++
 drivers/net/wwan/iosm/iosm_ipc_trace.h | 5 +++++
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem.c b/drivers/net/wwan/iosm/iosm_ipc_imem.c
index 49bdadb855e5..a60b93cefd2e 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem.c
@@ -272,7 +272,7 @@ static void ipc_imem_dl_skb_process(struct iosm_imem *ipc_imem,
 		if (port_id == IPC_MEM_CTRL_CHL_ID_7)
 			ipc_imem_sys_devlink_notify_rx(ipc_imem->ipc_devlink,
 						       skb);
-		else if (port_id == ipc_imem->trace->chl_id)
+		else if (ipc_is_trace_channel(ipc_imem, port_id))
 			ipc_trace_port_rx(ipc_imem->trace, skb);
 		else
 			wwan_port_rx(ipc_imem->ipc_port[port_id]->iosm_port,
@@ -555,10 +555,8 @@ static void ipc_imem_run_state_worker(struct work_struct *instance)
 	}
 
 	ipc_imem->trace = ipc_trace_init(ipc_imem);
-	if (!ipc_imem->trace) {
-		dev_err(ipc_imem->dev, "trace channel init failed");
-		return;
-	}
+	if (!ipc_imem->trace)
+		dev_warn(ipc_imem->dev, "trace channel init failed");
 
 	ipc_task_queue_send_task(ipc_imem, ipc_imem_send_mdm_rdy_cb, 0, NULL, 0,
 				 false);
diff --git a/drivers/net/wwan/iosm/iosm_ipc_trace.c b/drivers/net/wwan/iosm/iosm_ipc_trace.c
index 5f5cfd39bede..c588a394cd94 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_trace.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_trace.c
@@ -172,6 +172,9 @@ struct iosm_trace *ipc_trace_init(struct iosm_imem *ipc_imem)
  */
 void ipc_trace_deinit(struct iosm_trace *ipc_trace)
 {
+	if (!ipc_trace)
+		return;
+
 	debugfs_remove(ipc_trace->ctrl_file);
 	relay_close(ipc_trace->ipc_rchan);
 	mutex_destroy(&ipc_trace->trc_mutex);
diff --git a/drivers/net/wwan/iosm/iosm_ipc_trace.h b/drivers/net/wwan/iosm/iosm_ipc_trace.h
index 53346183af9c..419540c91219 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_trace.h
+++ b/drivers/net/wwan/iosm/iosm_ipc_trace.h
@@ -45,6 +45,11 @@ struct iosm_trace {
 	enum trace_ctrl_mode mode;
 };
 
+static inline bool ipc_is_trace_channel(struct iosm_imem *ipc_mem, u16 chl_id)
+{
+	return ipc_mem->trace && ipc_mem->trace->chl_id == chl_id;
+}
+
 struct iosm_trace *ipc_trace_init(struct iosm_imem *ipc_imem);
 void ipc_trace_deinit(struct iosm_trace *ipc_trace);
 void ipc_trace_port_rx(struct iosm_trace *ipc_trace, struct sk_buff *skb);
-- 
2.32.0

[PATCH RESEND net-next v2 3/4] net: wwan: iosm: move debugfs knobs into a subdir

[Sergey Ryazanov]

The modem traces collection is a device (and so driver) specific option.
Therefore, move the related debugfs files into a driver-specific
subdirectory under the common per WWAN device directory.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
---
Changes since v1:
* add missed description for a new structure field 'debugfs_dir'

 drivers/net/wwan/iosm/Makefile           |  1 +
 drivers/net/wwan/iosm/iosm_ipc_debugfs.c | 29 ++++++++++++++++++++++++
 drivers/net/wwan/iosm/iosm_ipc_debugfs.h | 12 ++++++++++
 drivers/net/wwan/iosm/iosm_ipc_imem.c    |  7 +++---
 drivers/net/wwan/iosm/iosm_ipc_imem.h    |  2 ++
 drivers/net/wwan/iosm/iosm_ipc_trace.c   |  6 ++---
 6 files changed, 49 insertions(+), 8 deletions(-)
 create mode 100644 drivers/net/wwan/iosm/iosm_ipc_debugfs.c
 create mode 100644 drivers/net/wwan/iosm/iosm_ipc_debugfs.h

diff --git a/drivers/net/wwan/iosm/Makefile b/drivers/net/wwan/iosm/Makefile
index 5c2528beca2a..5091f664af0d 100644
--- a/drivers/net/wwan/iosm/Makefile
+++ b/drivers/net/wwan/iosm/Makefile
@@ -22,6 +22,7 @@ iosm-y = \
 	iosm_ipc_devlink.o		\
 	iosm_ipc_flash.o		\
 	iosm_ipc_coredump.o		\
+	iosm_ipc_debugfs.o		\
 	iosm_ipc_trace.o
 
 obj-$(CONFIG_IOSM) := iosm.o
diff --git a/drivers/net/wwan/iosm/iosm_ipc_debugfs.c b/drivers/net/wwan/iosm/iosm_ipc_debugfs.c
new file mode 100644
index 000000000000..f2f57751a7d2
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_debugfs.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020-2021 Intel Corporation.
+ */
+
+#include <linux/debugfs.h>
+#include <linux/wwan.h>
+
+#include "iosm_ipc_imem.h"
+#include "iosm_ipc_trace.h"
+#include "iosm_ipc_debugfs.h"
+
+void ipc_debugfs_init(struct iosm_imem *ipc_imem)
+{
+	struct dentry *debugfs_pdev = wwan_get_debugfs_dir(ipc_imem->dev);
+
+	ipc_imem->debugfs_dir = debugfs_create_dir(KBUILD_MODNAME,
+						   debugfs_pdev);
+
+	ipc_imem->trace = ipc_trace_init(ipc_imem);
+	if (!ipc_imem->trace)
+		dev_warn(ipc_imem->dev, "trace channel init failed");
+}
+
+void ipc_debugfs_deinit(struct iosm_imem *ipc_imem)
+{
+	ipc_trace_deinit(ipc_imem->trace);
+	debugfs_remove_recursive(ipc_imem->debugfs_dir);
+}
diff --git a/drivers/net/wwan/iosm/iosm_ipc_debugfs.h b/drivers/net/wwan/iosm/iosm_ipc_debugfs.h
new file mode 100644
index 000000000000..35788039f13f
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_debugfs.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0-only
+ *
+ * Copyright (C) 2020-2021 Intel Corporation.
+ */
+
+#ifndef IOSM_IPC_DEBUGFS_H
+#define IOSM_IPC_DEBUGFS_H
+
+void ipc_debugfs_init(struct iosm_imem *ipc_imem);
+void ipc_debugfs_deinit(struct iosm_imem *ipc_imem);
+
+#endif
diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem.c b/drivers/net/wwan/iosm/iosm_ipc_imem.c
index a60b93cefd2e..25b889922912 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem.c
@@ -11,6 +11,7 @@
 #include "iosm_ipc_imem.h"
 #include "iosm_ipc_port.h"
 #include "iosm_ipc_trace.h"
+#include "iosm_ipc_debugfs.h"
 
 /* Check the wwan ips if it is valid with Channel as input. */
 static int ipc_imem_check_wwan_ips(struct ipc_mem_channel *chnl)
@@ -554,9 +555,7 @@ static void ipc_imem_run_state_worker(struct work_struct *instance)
 		ctrl_chl_idx++;
 	}
 
-	ipc_imem->trace = ipc_trace_init(ipc_imem);
-	if (!ipc_imem->trace)
-		dev_warn(ipc_imem->dev, "trace channel init failed");
+	ipc_debugfs_init(ipc_imem);
 
 	ipc_task_queue_send_task(ipc_imem, ipc_imem_send_mdm_rdy_cb, 0, NULL, 0,
 				 false);
@@ -1173,7 +1172,7 @@ void ipc_imem_cleanup(struct iosm_imem *ipc_imem)
 
 	if (test_and_clear_bit(FULLY_FUNCTIONAL, &ipc_imem->flag)) {
 		ipc_mux_deinit(ipc_imem->mux);
-		ipc_trace_deinit(ipc_imem->trace);
+		ipc_debugfs_deinit(ipc_imem);
 		ipc_wwan_deinit(ipc_imem->wwan);
 		ipc_port_deinit(ipc_imem->ipc_port);
 	}
diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem.h b/drivers/net/wwan/iosm/iosm_ipc_imem.h
index cec38009c44a..1b8c7b8959c6 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem.h
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem.h
@@ -341,6 +341,7 @@ enum ipc_phase {
  * @ev_mux_net_transmit_pending:0 means inform the IPC tasklet to pass
  * @reset_det_n:		Reset detect flag
  * @pcie_wake_n:		Pcie wake flag
+ * @debugfs_dir:		Debug FS directory for driver-specific entries
  */
 struct iosm_imem {
 	struct iosm_mmio *mmio;
@@ -380,6 +381,7 @@ struct iosm_imem {
 	   ev_mux_net_transmit_pending:1,
 	   reset_det_n:1,
 	   pcie_wake_n:1;
+	struct dentry *debugfs_dir;
 };
 
 /**
diff --git a/drivers/net/wwan/iosm/iosm_ipc_trace.c b/drivers/net/wwan/iosm/iosm_ipc_trace.c
index c588a394cd94..5243ead90b5f 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_trace.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_trace.c
@@ -134,7 +134,6 @@ struct iosm_trace *ipc_trace_init(struct iosm_imem *ipc_imem)
 {
 	struct ipc_chnl_cfg chnl_cfg = { 0 };
 	struct iosm_trace *ipc_trace;
-	struct dentry *debugfs_pdev;
 
 	ipc_chnl_cfg_get(&chnl_cfg, IPC_MEM_CTRL_CHL_ID_3);
 	ipc_imem_channel_init(ipc_imem, IPC_CTYPE_CTRL, chnl_cfg,
@@ -150,15 +149,14 @@ struct iosm_trace *ipc_trace_init(struct iosm_imem *ipc_imem)
 	ipc_trace->chl_id = IPC_MEM_CTRL_CHL_ID_3;
 
 	mutex_init(&ipc_trace->trc_mutex);
-	debugfs_pdev = wwan_get_debugfs_dir(ipc_imem->dev);
 
 	ipc_trace->ctrl_file = debugfs_create_file(IOSM_TRC_DEBUGFS_TRACE_CTRL,
 						   IOSM_TRC_FILE_PERM,
-						   debugfs_pdev,
+						   ipc_imem->debugfs_dir,
 						   ipc_trace, &ipc_trace_fops);
 
 	ipc_trace->ipc_rchan = relay_open(IOSM_TRC_DEBUGFS_TRACE,
-					  debugfs_pdev,
+					  ipc_imem->debugfs_dir,
 					  IOSM_TRC_SUB_BUFF_SIZE,
 					  IOSM_TRC_N_SUB_BUFF,
 					  &relay_callbacks, NULL);
-- 
2.32.0

[PATCH RESEND net-next v2 4/4] net: wwan: make debugfs optional

[Sergey Ryazanov]

Debugfs interface is optional for the regular modem use. Some distros
and users will want to disable this feature for security or kernel
size reasons. So add a configuration option that allows to completely
disable the debugfs interface of the WWAN devices.

A primary considered use case for this option was embedded firmwares.
For example, in OpenWrt, you can not completely disable debugfs, as a
lot of wireless stuff can only be configured and monitored with the
debugfs knobs. At the same time, reducing the size of a kernel and
modules is an essential task in the world of embedded software.
Disabling the WWAN and IOSM debugfs interfaces allows us to save 50K
(x86-64 build) of space for module storage. Not much, but already
considerable when you only have 16MB of storage.

So it is hard to just disable whole debugfs. Users need some fine
grained set of options to control which debugfs interface is important
and should be available and which is not.

The new configuration symbol is enabled by default and is hidden under
the EXPERT option. So a regular user would not be bothered by another
one configuration question. While an embedded distro maintainer will be
able to a little more reduce the final image size.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
---
Changes since v1:
* this is a merge of 4th and 5th patches
* drop the IOSM specific configuration option and use the common WWAN
  option to control the IOSM debugfs interface build, thanks to Johannes
  and Leon for their recomendations
* make WWAN debugfs enabled by default and hide it under EXPERT as
  suggested by Johannes
* add  a detailed rationale to the patch description to show why we need
  the ability to disable debugfs
* return ERR_PTR(-ENODEV) instead of NULL if WWAN debugfs was disabled,
  thanks to Johannes for spotting this
* fix unused 'wwandev_name' variable warning
* expand the new configuration symbold description

 drivers/net/wwan/Kconfig                 | 13 ++++++++++++-
 drivers/net/wwan/iosm/Makefile           |  4 +++-
 drivers/net/wwan/iosm/iosm_ipc_debugfs.h |  5 +++++
 drivers/net/wwan/iosm/iosm_ipc_imem.c    |  2 +-
 drivers/net/wwan/iosm/iosm_ipc_imem.h    |  4 ++++
 drivers/net/wwan/iosm/iosm_ipc_trace.c   |  6 ++++--
 drivers/net/wwan/iosm/iosm_ipc_trace.h   | 20 +++++++++++++++++++-
 drivers/net/wwan/wwan_core.c             | 17 +++++++++++++----
 include/linux/wwan.h                     |  7 +++++++
 9 files changed, 68 insertions(+), 10 deletions(-)

diff --git a/drivers/net/wwan/Kconfig b/drivers/net/wwan/Kconfig
index 9f5111a77da9..609fd4a2c865 100644
--- a/drivers/net/wwan/Kconfig
+++ b/drivers/net/wwan/Kconfig
@@ -16,6 +16,17 @@ config WWAN
 
 if WWAN
 
+config WWAN_DEBUGFS
+	bool "WWAN devices debugfs interface" if EXPERT
+	depends on DEBUG_FS
+	default y
+	help
+	  Enables debugfs infrastructure for the WWAN core and device drivers.
+
+	  If this option is selected, then you can find the debug interface
+	  elements for each WWAN device in a directory that is corresponding to
+	  the device name: debugfs/wwan/wwanX.
+
 config WWAN_HWSIM
 	tristate "Simulated WWAN device"
 	help
@@ -85,7 +96,7 @@ config IOSM
 	tristate "IOSM Driver for Intel M.2 WWAN Device"
 	depends on INTEL_IOMMU
 	select NET_DEVLINK
-	select RELAY
+	select RELAY if WWAN_DEBUGFS
 	help
 	  This driver enables Intel M.2 WWAN Device communication.
 
diff --git a/drivers/net/wwan/iosm/Makefile b/drivers/net/wwan/iosm/Makefile
index 5091f664af0d..fa8d6afd18e1 100644
--- a/drivers/net/wwan/iosm/Makefile
+++ b/drivers/net/wwan/iosm/Makefile
@@ -21,7 +21,9 @@ iosm-y = \
 	iosm_ipc_mux_codec.o		\
 	iosm_ipc_devlink.o		\
 	iosm_ipc_flash.o		\
-	iosm_ipc_coredump.o		\
+	iosm_ipc_coredump.o
+
+iosm-$(CONFIG_WWAN_DEBUGFS) += \
 	iosm_ipc_debugfs.o		\
 	iosm_ipc_trace.o
 
diff --git a/drivers/net/wwan/iosm/iosm_ipc_debugfs.h b/drivers/net/wwan/iosm/iosm_ipc_debugfs.h
index 35788039f13f..8a84bfa2c14a 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_debugfs.h
+++ b/drivers/net/wwan/iosm/iosm_ipc_debugfs.h
@@ -6,7 +6,12 @@
 #ifndef IOSM_IPC_DEBUGFS_H
 #define IOSM_IPC_DEBUGFS_H
 
+#ifdef CONFIG_WWAN_DEBUGFS
 void ipc_debugfs_init(struct iosm_imem *ipc_imem);
 void ipc_debugfs_deinit(struct iosm_imem *ipc_imem);
+#else
+static inline void ipc_debugfs_init(struct iosm_imem *ipc_imem) {}
+static inline void ipc_debugfs_deinit(struct iosm_imem *ipc_imem) {}
+#endif
 
 #endif
diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem.c b/drivers/net/wwan/iosm/iosm_ipc_imem.c
index 25b889922912..2a6ddd7c6c88 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem.c
@@ -274,7 +274,7 @@ static void ipc_imem_dl_skb_process(struct iosm_imem *ipc_imem,
 			ipc_imem_sys_devlink_notify_rx(ipc_imem->ipc_devlink,
 						       skb);
 		else if (ipc_is_trace_channel(ipc_imem, port_id))
-			ipc_trace_port_rx(ipc_imem->trace, skb);
+			ipc_trace_port_rx(ipc_imem, skb);
 		else
 			wwan_port_rx(ipc_imem->ipc_port[port_id]->iosm_port,
 				     skb);
diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem.h b/drivers/net/wwan/iosm/iosm_ipc_imem.h
index 1b8c7b8959c6..86a1ffe61729 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem.h
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem.h
@@ -351,7 +351,9 @@ struct iosm_imem {
 	struct iosm_mux *mux;
 	struct iosm_cdev *ipc_port[IPC_MEM_MAX_CHANNELS];
 	struct iosm_pcie *pcie;
+#ifdef CONFIG_WWAN_DEBUGFS
 	struct iosm_trace *trace;
+#endif
 	struct device *dev;
 	enum ipc_mem_device_ipc_state ipc_requested_state;
 	struct ipc_mem_channel channels[IPC_MEM_MAX_CHANNELS];
@@ -381,7 +383,9 @@ struct iosm_imem {
 	   ev_mux_net_transmit_pending:1,
 	   reset_det_n:1,
 	   pcie_wake_n:1;
+#ifdef CONFIG_WWAN_DEBUGFS
 	struct dentry *debugfs_dir;
+#endif
 };
 
 /**
diff --git a/drivers/net/wwan/iosm/iosm_ipc_trace.c b/drivers/net/wwan/iosm/iosm_ipc_trace.c
index 5243ead90b5f..eeecfa3d10c5 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_trace.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_trace.c
@@ -17,11 +17,13 @@
 
 /**
  * ipc_trace_port_rx - Receive trace packet from cp and write to relay buffer
- * @ipc_trace:  Pointer to the ipc trace data-struct
+ * @ipc_imem:   Pointer to iosm_imem structure
  * @skb:        Pointer to struct sk_buff
  */
-void ipc_trace_port_rx(struct iosm_trace *ipc_trace, struct sk_buff *skb)
+void ipc_trace_port_rx(struct iosm_imem *ipc_imem, struct sk_buff *skb)
 {
+	struct iosm_trace *ipc_trace = ipc_imem->trace;
+
 	if (ipc_trace->ipc_rchan)
 		relay_write(ipc_trace->ipc_rchan, skb->data, skb->len);
 
diff --git a/drivers/net/wwan/iosm/iosm_ipc_trace.h b/drivers/net/wwan/iosm/iosm_ipc_trace.h
index 419540c91219..5ebe7790585c 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_trace.h
+++ b/drivers/net/wwan/iosm/iosm_ipc_trace.h
@@ -45,6 +45,8 @@ struct iosm_trace {
 	enum trace_ctrl_mode mode;
 };
 
+#ifdef CONFIG_WWAN_DEBUGFS
+
 static inline bool ipc_is_trace_channel(struct iosm_imem *ipc_mem, u16 chl_id)
 {
 	return ipc_mem->trace && ipc_mem->trace->chl_id == chl_id;
@@ -52,5 +54,21 @@ static inline bool ipc_is_trace_channel(struct iosm_imem *ipc_mem, u16 chl_id)
 
 struct iosm_trace *ipc_trace_init(struct iosm_imem *ipc_imem);
 void ipc_trace_deinit(struct iosm_trace *ipc_trace);
-void ipc_trace_port_rx(struct iosm_trace *ipc_trace, struct sk_buff *skb);
+void ipc_trace_port_rx(struct iosm_imem *ipc_imem, struct sk_buff *skb);
+
+#else
+
+static inline bool ipc_is_trace_channel(struct iosm_imem *ipc_mem, u16 chl_id)
+{
+	return false;
+}
+
+static inline void ipc_trace_port_rx(struct iosm_imem *ipc_imem,
+				     struct sk_buff *skb)
+{
+	dev_kfree_skb(skb);
+}
+
+#endif
+
 #endif
diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index 5bf62dc35ac7..1508dc2a497b 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -50,7 +50,9 @@ struct wwan_device {
 	atomic_t port_id;
 	const struct wwan_ops *ops;
 	void *ops_ctxt;
+#ifdef CONFIG_WWAN_DEBUGFS
 	struct dentry *debugfs_dir;
+#endif
 };
 
 /**
@@ -146,6 +148,7 @@ static struct wwan_device *wwan_dev_get_by_name(const char *name)
 	return to_wwan_dev(dev);
 }
 
+#ifdef CONFIG_WWAN_DEBUGFS
 struct dentry *wwan_get_debugfs_dir(struct device *parent)
 {
 	struct wwan_device *wwandev;
@@ -157,6 +160,7 @@ struct dentry *wwan_get_debugfs_dir(struct device *parent)
 	return wwandev->debugfs_dir;
 }
 EXPORT_SYMBOL_GPL(wwan_get_debugfs_dir);
+#endif
 
 /* This function allocates and registers a new WWAN device OR if a WWAN device
  * already exist for the given parent, it gets a reference and return it.
@@ -166,7 +170,6 @@ EXPORT_SYMBOL_GPL(wwan_get_debugfs_dir);
 static struct wwan_device *wwan_create_dev(struct device *parent)
 {
 	struct wwan_device *wwandev;
-	const char *wwandev_name;
 	int err, id;
 
 	/* The 'find-alloc-register' operation must be protected against
@@ -206,9 +209,11 @@ static struct wwan_device *wwan_create_dev(struct device *parent)
 		goto done_unlock;
 	}
 
-	wwandev_name = kobject_name(&wwandev->dev.kobj);
-	wwandev->debugfs_dir = debugfs_create_dir(wwandev_name,
-						  wwan_debugfs_dir);
+#ifdef CONFIG_WWAN_DEBUGFS
+	wwandev->debugfs_dir =
+			debugfs_create_dir(kobject_name(&wwandev->dev.kobj),
+					   wwan_debugfs_dir);
+#endif
 
 done_unlock:
 	mutex_unlock(&wwan_register_lock);
@@ -240,7 +245,9 @@ static void wwan_remove_dev(struct wwan_device *wwandev)
 		ret = device_for_each_child(&wwandev->dev, NULL, is_wwan_child);
 
 	if (!ret) {
+#ifdef CONFIG_WWAN_DEBUGFS
 		debugfs_remove_recursive(wwandev->debugfs_dir);
+#endif
 		device_unregister(&wwandev->dev);
 	} else {
 		put_device(&wwandev->dev);
@@ -1140,7 +1147,9 @@ static int __init wwan_init(void)
 		goto destroy;
 	}
 
+#ifdef CONFIG_WWAN_DEBUGFS
 	wwan_debugfs_dir = debugfs_create_dir("wwan", NULL);
+#endif
 
 	return 0;
 
diff --git a/include/linux/wwan.h b/include/linux/wwan.h
index 1646aa3e6779..e143c88bf4b0 100644
--- a/include/linux/wwan.h
+++ b/include/linux/wwan.h
@@ -171,6 +171,13 @@ int wwan_register_ops(struct device *parent, const struct wwan_ops *ops,
 
 void wwan_unregister_ops(struct device *parent);
 
+#ifdef CONFIG_WWAN_DEBUGFS
 struct dentry *wwan_get_debugfs_dir(struct device *parent);
+#else
+static inline struct dentry *wwan_get_debugfs_dir(struct device *parent)
+{
+	return ERR_PTR(-ENODEV);
+}
+#endif
 
 #endif /* __WWAN_H */
-- 
2.32.0

Re: [PATCH RESEND net-next v2 0/4] WWAN debugfs tweaks

[Loic Poulain]

On Tue, 7 Dec 2021 at 10:21, Sergey Ryazanov <ryazanov.s.a@gmail.com> wrote:
>
> Resent after dependency [2] was merged to the net-next tree. Added
> Leon's reviewed-by tag from the first V2 submission.
>
> This is a follow-up series to just applied IOSM (and WWAN) debugfs
> interface support [1]. The series has two main goals:
> 1. move the driver-specific debugfs knobs to a subdirectory;
> 2. make the debugfs interface optional for both IOSM and for the WWAN
>    core.
>
> As for the first part, I must say that it was my mistake. I suggested to
> place debugfs entries under a common per WWAN device directory. But I
> missed the driver subdirectory in the example, so it become:
>
> /sys/kernel/debugfs/wwan/wwan0/trace
>
> Since the traces collection is a driver-specific feature, it is better
> to keep it under the driver-specific subdirectory:
>
> /sys/kernel/debugfs/wwan/wwan0/iosm/trace
>
> It is desirable to be able to entirely disable the debugfs interface. It
> can be disabled for several reasons, including security and consumed
> storage space. See detailed rationale with usage example in the 4th
> patch.
>
> The changes themselves are relatively simple, but require a code
> rearrangement. So to make changes clear, I chose to split them into
> preparatory and main changes and properly describe each of them.
>
> IOSM part is compile-tested only since I do not have IOSM supported
> device, so it needs Ack from the driver developers.
>
> I would like to thank Johannes Berg and Leon Romanovsky. Their
> suggestions and comments helped a lot to rework the initial
> over-engineered solution to something less confusing and much more
> simple. Thanks!

Looks good.

Reviewed-by: Loic Poulain <loic.poulain@linaro.org>

RE: [PATCH RESEND net-next v2 0/4] WWAN debugfs tweaks

[Kumar, M Chetan]

> -----Original Message-----
> From: Sergey Ryazanov <ryazanov.s.a@gmail.com>
> Sent: Tuesday, December 7, 2021 2:52 PM
> To: David S . Miller <davem@davemloft.net>; Jakub Kicinski
> <kuba@kernel.org>
> Cc: netdev@vger.kernel.org; Kumar, M Chetan
> <m.chetan.kumar@intel.com>; linuxwwan <linuxwwan@intel.com>; Loic
> Poulain <loic.poulain@linaro.org>; Johannes Berg
> <johannes@sipsolutions.net>; Leon Romanovsky <leon@kernel.org>
> Subject: [PATCH RESEND net-next v2 0/4] WWAN debugfs tweaks
> 
> Resent after dependency [2] was merged to the net-next tree. Added Leon's
> reviewed-by tag from the first V2 submission.
> 
> This is a follow-up series to just applied IOSM (and WWAN) debugfs interface
> support [1]. The series has two main goals:
> 1. move the driver-specific debugfs knobs to a subdirectory; 2. make the
> debugfs interface optional for both IOSM and for the WWAN
>    core.
> 
> As for the first part, I must say that it was my mistake. I suggested to place
> debugfs entries under a common per WWAN device directory. But I missed
> the driver subdirectory in the example, so it become:
> 
> /sys/kernel/debugfs/wwan/wwan0/trace
> 
> Since the traces collection is a driver-specific feature, it is better to keep it
> under the driver-specific subdirectory:
> 
> /sys/kernel/debugfs/wwan/wwan0/iosm/trace
> 
> It is desirable to be able to entirely disable the debugfs interface. It can be
> disabled for several reasons, including security and consumed storage space.
> See detailed rationale with usage example in the 4th patch.
> 
> The changes themselves are relatively simple, but require a code
> rearrangement. So to make changes clear, I chose to split them into
> preparatory and main changes and properly describe each of them.
> 
> IOSM part is compile-tested only since I do not have IOSM supported device,
> so it needs Ack from the driver developers.
> 
> I would like to thank Johannes Berg and Leon Romanovsky. Their suggestions
> and comments helped a lot to rework the initial over-engineered solution to
> something less confusing and much more simple. Thanks!
> 
> Changes since v1:
> * 1st and 2nd patches were not changed
> * add missed field description in the 3rd patch
> * 4th and 5th patches have been merged into a single one with rework of
>   the configuration options and and a few other fixes (see detailed
>   changelog in the patch)
> 
> 1. https://lore.kernel.org/netdev/20211120162155.1216081-1-
> m.chetan.kumar@linux.intel.com
> 2.
> https://patchwork.kernel.org/project/netdevbpf/patch/20211204174033.950
> 528-1-arnd@kernel.org/

Acked-by: M Chetan Kumar <m.chetan.kumar@intel.com>

Re: [PATCH RESEND net-next v2 0/4] WWAN debugfs tweaks

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Tue,  7 Dec 2021 12:21:36 +0300 you wrote:
> Resent after dependency [2] was merged to the net-next tree. Added
> Leon's reviewed-by tag from the first V2 submission.
> 
> This is a follow-up series to just applied IOSM (and WWAN) debugfs
> interface support [1]. The series has two main goals:
> 1. move the driver-specific debugfs knobs to a subdirectory;
> 2. make the debugfs interface optional for both IOSM and for the WWAN
>    core.
> 
> [...]

Here is the summary with links:
  - [RESEND,net-next,v2,1/4] net: wwan: iosm: consolidate trace port init code
    https://git.kernel.org/netdev/net-next/c/e9877d4ef856
  - [RESEND,net-next,v2,2/4] net: wwan: iosm: allow trace port be uninitialized
    https://git.kernel.org/netdev/net-next/c/13b94fbaa28c
  - [RESEND,net-next,v2,3/4] net: wwan: iosm: move debugfs knobs into a subdir
    https://git.kernel.org/netdev/net-next/c/cf90098dbb1f
  - [RESEND,net-next,v2,4/4] net: wwan: make debugfs optional
    https://git.kernel.org/netdev/net-next/c/283e6f5a8166

You are awesome, thank you!
-- 
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