diff mbox series

[v2] printk: Add a short description string to kmsg_dump()

Message ID 20240702122639.248110-1-jfalempe@redhat.com (mailing list archive)
State New
Headers show
Series [v2] printk: Add a short description string to kmsg_dump() | expand

Commit Message

Jocelyn Falempe July 2, 2024, 12:26 p.m. UTC
kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
callback.
This patch adds a new struct kmsg_dump_detail, that will hold the
reason and description, and pass it to the dump() callback.

To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
function and a macro for backward compatibility.

I've written this for drm_panic, but it can be useful for other
kmsg_dumper.
It allows to see the panic reason, like "sysrq triggered crash"
or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.

v2:
 * Use a struct kmsg_dump_detail to hold the reason and description
   pointer, for more flexibility if we want to add other parameters.
   (Kees Cook)
 * Fix powerpc/nvram_64 build, as I didn't update the forward
   declaration of oops_to_nvram()

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
---
 arch/powerpc/kernel/nvram_64.c             |  8 ++++----
 arch/powerpc/platforms/powernv/opal-kmsg.c |  4 ++--
 arch/um/kernel/kmsg_dump.c                 |  2 +-
 drivers/gpu/drm/drm_panic.c                |  4 ++--
 drivers/hv/hv_common.c                     |  4 ++--
 drivers/mtd/mtdoops.c                      |  2 +-
 fs/pstore/platform.c                       | 10 +++++-----
 include/linux/kmsg_dump.h                  | 22 +++++++++++++++++++---
 kernel/panic.c                             |  2 +-
 kernel/printk/printk.c                     | 11 ++++++++---
 10 files changed, 45 insertions(+), 24 deletions(-)


base-commit: 82e4255305c554b0bb18b7ccf2db86041b4c8b6e

Comments

Kees Cook July 2, 2024, 8:29 p.m. UTC | #1
On Tue, Jul 02, 2024 at 02:26:04PM +0200, Jocelyn Falempe wrote:
> kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
> callback.
> This patch adds a new struct kmsg_dump_detail, that will hold the
> reason and description, and pass it to the dump() callback.

Thanks! I like this much better. :)

> 
> To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
> function and a macro for backward compatibility.
> 
> I've written this for drm_panic, but it can be useful for other
> kmsg_dumper.
> It allows to see the panic reason, like "sysrq triggered crash"
> or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.
> 
> v2:
>  * Use a struct kmsg_dump_detail to hold the reason and description
>    pointer, for more flexibility if we want to add other parameters.
>    (Kees Cook)
>  * Fix powerpc/nvram_64 build, as I didn't update the forward
>    declaration of oops_to_nvram()

The versioning history commonly goes after the "---".

> [...]
> diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
> index 906521c2329c..65f5a47727bc 100644
> --- a/include/linux/kmsg_dump.h
> +++ b/include/linux/kmsg_dump.h
> @@ -39,6 +39,17 @@ struct kmsg_dump_iter {
>  	u64	next_seq;
>  };
>  
> +/**
> + *struct kmsg_dump_detail - kernel crash detail

Is kern-doc happy with this? I think there is supposed to be a space
between the "*" and the first word:

 /**
  * struct kmsg...


Otherwise looks good to me!
Jocelyn Falempe July 3, 2024, 7:57 a.m. UTC | #2
On 02/07/2024 22:29, Kees Cook wrote:
> On Tue, Jul 02, 2024 at 02:26:04PM +0200, Jocelyn Falempe wrote:
>> kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
>> callback.
>> This patch adds a new struct kmsg_dump_detail, that will hold the
>> reason and description, and pass it to the dump() callback.
> 
> Thanks! I like this much better. :)
> 
>>
>> To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
>> function and a macro for backward compatibility.
>>
>> I've written this for drm_panic, but it can be useful for other
>> kmsg_dumper.
>> It allows to see the panic reason, like "sysrq triggered crash"
>> or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.
>>
>> v2:
>>   * Use a struct kmsg_dump_detail to hold the reason and description
>>     pointer, for more flexibility if we want to add other parameters.
>>     (Kees Cook)
>>   * Fix powerpc/nvram_64 build, as I didn't update the forward
>>     declaration of oops_to_nvram()
> 
> The versioning history commonly goes after the "---".

ok, I was not aware of this.
> 
>> [...]
>> diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
>> index 906521c2329c..65f5a47727bc 100644
>> --- a/include/linux/kmsg_dump.h
>> +++ b/include/linux/kmsg_dump.h
>> @@ -39,6 +39,17 @@ struct kmsg_dump_iter {
>>   	u64	next_seq;
>>   };
>>   
>> +/**
>> + *struct kmsg_dump_detail - kernel crash detail
> 
> Is kern-doc happy with this? I think there is supposed to be a space
> between the "*" and the first word:
> 
>   /**
>    * struct kmsg...
> 
> 
Good catch, yes there is a space missing.

I just checked with "make htmldocs", and in fact 
include/linux/kmsg_dump.h is not indexed for kernel documentation.
And you can't find the definition of struct kmsg_dumper in the online doc.
https://www.kernel.org/doc/html/latest/search.html?q=kmsg_dumper

> Otherwise looks good to me!
> 

Thanks.

As this patch touches different subsystems, do you know on which tree it 
should land ?
Petr Mladek July 3, 2024, 8:12 a.m. UTC | #3
On Tue 2024-07-02 14:26:04, Jocelyn Falempe wrote:
> kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
> callback.
> This patch adds a new struct kmsg_dump_detail, that will hold the
> reason and description, and pass it to the dump() callback.
> 
> To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
> function and a macro for backward compatibility.
> 
> I've written this for drm_panic, but it can be useful for other
> kmsg_dumper.
> It allows to see the panic reason, like "sysrq triggered crash"
> or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.
> 
> v2:
>  * Use a struct kmsg_dump_detail to hold the reason and description
>    pointer, for more flexibility if we want to add other parameters.
>    (Kees Cook)
>  * Fix powerpc/nvram_64 build, as I didn't update the forward
>    declaration of oops_to_nvram()
> 
> Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>

Looks good to me. With the minor fixes suggested by Kees:

Acked-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr
Petr Mladek July 3, 2024, 8:22 a.m. UTC | #4
On Wed 2024-07-03 09:57:26, Jocelyn Falempe wrote:
> 
> 
> On 02/07/2024 22:29, Kees Cook wrote:
> > On Tue, Jul 02, 2024 at 02:26:04PM +0200, Jocelyn Falempe wrote:
> > > kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
> > > callback.
> > > This patch adds a new struct kmsg_dump_detail, that will hold the
> > > reason and description, and pass it to the dump() callback.
> > 
> > Thanks! I like this much better. :)
> > 
> > > 
> > > To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
> > > function and a macro for backward compatibility.
> > > 
> > > I've written this for drm_panic, but it can be useful for other
> > > kmsg_dumper.
> > > It allows to see the panic reason, like "sysrq triggered crash"
> > > or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.
> > > 
> > > v2:
> > >   * Use a struct kmsg_dump_detail to hold the reason and description
> > >     pointer, for more flexibility if we want to add other parameters.
> > >     (Kees Cook)
> > >   * Fix powerpc/nvram_64 build, as I didn't update the forward
> > >     declaration of oops_to_nvram()
> > 
> > The versioning history commonly goes after the "---".
> 
> ok, I was not aware of this.
> > 
> > > [...]
> > > diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
> > > index 906521c2329c..65f5a47727bc 100644
> > > --- a/include/linux/kmsg_dump.h
> > > +++ b/include/linux/kmsg_dump.h
> > > @@ -39,6 +39,17 @@ struct kmsg_dump_iter {
> > >   	u64	next_seq;
> > >   };
> > > +/**
> > > + *struct kmsg_dump_detail - kernel crash detail
> > 
> > Is kern-doc happy with this? I think there is supposed to be a space
> > between the "*" and the first word:
> > 
> >   /**
> >    * struct kmsg...
> > 
> > 
> Good catch, yes there is a space missing.
> 
> I just checked with "make htmldocs", and in fact include/linux/kmsg_dump.h
> is not indexed for kernel documentation.
> And you can't find the definition of struct kmsg_dumper in the online doc.
> https://www.kernel.org/doc/html/latest/search.html?q=kmsg_dumper
> 
> > Otherwise looks good to me!
> > 
> 
> Thanks.
> 
> As this patch touches different subsystems, do you know on which tree it
> should land ?

Andrew usually takes patches against kernel/panic.c.

Or you could take it via the DRM tree, especially if you already have the code
using the string.

Also I could take it via the printk tree. The only complication is
that I am going to be away the following two weeks and would come
back in the middle of the merge window. I do not expect much problems
with this change but...

Best Regards,
Petr
Kees Cook July 3, 2024, 4:27 p.m. UTC | #5
On Wed, Jul 03, 2024 at 10:22:11AM +0200, Petr Mladek wrote:
> On Wed 2024-07-03 09:57:26, Jocelyn Falempe wrote:
> > 
> > 
> > On 02/07/2024 22:29, Kees Cook wrote:
> > > On Tue, Jul 02, 2024 at 02:26:04PM +0200, Jocelyn Falempe wrote:
> > > > kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
> > > > callback.
> > > > This patch adds a new struct kmsg_dump_detail, that will hold the
> > > > reason and description, and pass it to the dump() callback.
> > > 
> > > Thanks! I like this much better. :)
> > > 
> > > > 
> > > > To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
> > > > function and a macro for backward compatibility.
> > > > 
> > > > I've written this for drm_panic, but it can be useful for other
> > > > kmsg_dumper.
> > > > It allows to see the panic reason, like "sysrq triggered crash"
> > > > or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.
> > > > 
> > > > v2:
> > > >   * Use a struct kmsg_dump_detail to hold the reason and description
> > > >     pointer, for more flexibility if we want to add other parameters.
> > > >     (Kees Cook)
> > > >   * Fix powerpc/nvram_64 build, as I didn't update the forward
> > > >     declaration of oops_to_nvram()
> > > 
> > > The versioning history commonly goes after the "---".
> > 
> > ok, I was not aware of this.
> > > 
> > > > [...]
> > > > diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
> > > > index 906521c2329c..65f5a47727bc 100644
> > > > --- a/include/linux/kmsg_dump.h
> > > > +++ b/include/linux/kmsg_dump.h
> > > > @@ -39,6 +39,17 @@ struct kmsg_dump_iter {
> > > >   	u64	next_seq;
> > > >   };
> > > > +/**
> > > > + *struct kmsg_dump_detail - kernel crash detail
> > > 
> > > Is kern-doc happy with this? I think there is supposed to be a space
> > > between the "*" and the first word:
> > > 
> > >   /**
> > >    * struct kmsg...
> > > 
> > > 
> > Good catch, yes there is a space missing.
> > 
> > I just checked with "make htmldocs", and in fact include/linux/kmsg_dump.h
> > is not indexed for kernel documentation.
> > And you can't find the definition of struct kmsg_dumper in the online doc.
> > https://www.kernel.org/doc/html/latest/search.html?q=kmsg_dumper
> > 
> > > Otherwise looks good to me!
> > > 
> > 
> > Thanks.
> > 
> > As this patch touches different subsystems, do you know on which tree it
> > should land ?
> 
> Andrew usually takes patches against kernel/panic.c.
> 
> Or you could take it via the DRM tree, especially if you already have the code
> using the string.
> 
> Also I could take it via the printk tree. The only complication is
> that I am going to be away the following two weeks and would come
> back in the middle of the merge window. I do not expect much problems
> with this change but...

If DRM doesn't want to carry it, I can put it in through the pstore
tree. Let me know! :)
Jocelyn Falempe July 3, 2024, 4:40 p.m. UTC | #6
On 03/07/2024 18:27, Kees Cook wrote:
> On Wed, Jul 03, 2024 at 10:22:11AM +0200, Petr Mladek wrote:
>> On Wed 2024-07-03 09:57:26, Jocelyn Falempe wrote:
>>>
>>>
>>> On 02/07/2024 22:29, Kees Cook wrote:
>>>> On Tue, Jul 02, 2024 at 02:26:04PM +0200, Jocelyn Falempe wrote:
>>>>> kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
>>>>> callback.
>>>>> This patch adds a new struct kmsg_dump_detail, that will hold the
>>>>> reason and description, and pass it to the dump() callback.
>>>>
>>>> Thanks! I like this much better. :)
>>>>
>>>>>
>>>>> To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
>>>>> function and a macro for backward compatibility.
>>>>>
>>>>> I've written this for drm_panic, but it can be useful for other
>>>>> kmsg_dumper.
>>>>> It allows to see the panic reason, like "sysrq triggered crash"
>>>>> or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.
>>>>>
>>>>> v2:
>>>>>    * Use a struct kmsg_dump_detail to hold the reason and description
>>>>>      pointer, for more flexibility if we want to add other parameters.
>>>>>      (Kees Cook)
>>>>>    * Fix powerpc/nvram_64 build, as I didn't update the forward
>>>>>      declaration of oops_to_nvram()
>>>>
>>>> The versioning history commonly goes after the "---".
>>>
>>> ok, I was not aware of this.
>>>>
>>>>> [...]
>>>>> diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
>>>>> index 906521c2329c..65f5a47727bc 100644
>>>>> --- a/include/linux/kmsg_dump.h
>>>>> +++ b/include/linux/kmsg_dump.h
>>>>> @@ -39,6 +39,17 @@ struct kmsg_dump_iter {
>>>>>    	u64	next_seq;
>>>>>    };
>>>>> +/**
>>>>> + *struct kmsg_dump_detail - kernel crash detail
>>>>
>>>> Is kern-doc happy with this? I think there is supposed to be a space
>>>> between the "*" and the first word:
>>>>
>>>>    /**
>>>>     * struct kmsg...
>>>>
>>>>
>>> Good catch, yes there is a space missing.
>>>
>>> I just checked with "make htmldocs", and in fact include/linux/kmsg_dump.h
>>> is not indexed for kernel documentation.
>>> And you can't find the definition of struct kmsg_dumper in the online doc.
>>> https://www.kernel.org/doc/html/latest/search.html?q=kmsg_dumper
>>>
>>>> Otherwise looks good to me!
>>>>
>>>
>>> Thanks.
>>>
>>> As this patch touches different subsystems, do you know on which tree it
>>> should land ?
>>
>> Andrew usually takes patches against kernel/panic.c.
>>
>> Or you could take it via the DRM tree, especially if you already have the code
>> using the string.

If it's not taken in Andrew's tree next week, I will see if I can push 
it to the drm-misc tree. I think there is a very low chance of conflicts.

>>
>> Also I could take it via the printk tree. The only complication is
>> that I am going to be away the following two weeks and would come
>> back in the middle of the merge window. I do not expect much problems
>> with this change but...
> 
> If DRM doesn't want to carry it, I can put it in through the pstore
> tree. Let me know! :)
> 

Thanks for the proposition, I will see how it goes, it would be nice to 
have it in time for the v6.11 merge window.

Best regards,
diff mbox series

Patch

diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
index e385d3164648..f9c6568a9137 100644
--- a/arch/powerpc/kernel/nvram_64.c
+++ b/arch/powerpc/kernel/nvram_64.c
@@ -73,7 +73,7 @@  static const char *nvram_os_partitions[] = {
 };
 
 static void oops_to_nvram(struct kmsg_dumper *dumper,
-			  enum kmsg_dump_reason reason);
+			  struct kmsg_dump_detail *detail);
 
 static struct kmsg_dumper nvram_kmsg_dumper = {
 	.dump = oops_to_nvram
@@ -643,7 +643,7 @@  void __init nvram_init_oops_partition(int rtas_partition_exists)
  * partition.  If that's too much, go back and capture uncompressed text.
  */
 static void oops_to_nvram(struct kmsg_dumper *dumper,
-			  enum kmsg_dump_reason reason)
+			  struct kmsg_dump_detail *detail)
 {
 	struct oops_log_info *oops_hdr = (struct oops_log_info *)oops_buf;
 	static unsigned int oops_count = 0;
@@ -655,7 +655,7 @@  static void oops_to_nvram(struct kmsg_dumper *dumper,
 	unsigned int err_type = ERR_TYPE_KERNEL_PANIC_GZ;
 	int rc = -1;
 
-	switch (reason) {
+	switch (detail->reason) {
 	case KMSG_DUMP_SHUTDOWN:
 		/* These are almost always orderly shutdowns. */
 		return;
@@ -671,7 +671,7 @@  static void oops_to_nvram(struct kmsg_dumper *dumper,
 		break;
 	default:
 		pr_err("%s: ignoring unrecognized KMSG_DUMP_* reason %d\n",
-		       __func__, (int) reason);
+		       __func__, (int) detail->reason);
 		return;
 	}
 
diff --git a/arch/powerpc/platforms/powernv/opal-kmsg.c b/arch/powerpc/platforms/powernv/opal-kmsg.c
index 6c3bc4b4da98..bb4218fa796e 100644
--- a/arch/powerpc/platforms/powernv/opal-kmsg.c
+++ b/arch/powerpc/platforms/powernv/opal-kmsg.c
@@ -20,13 +20,13 @@ 
  * message, it just ensures that OPAL completely flushes the console buffer.
  */
 static void kmsg_dump_opal_console_flush(struct kmsg_dumper *dumper,
-				     enum kmsg_dump_reason reason)
+				     struct kmsg_dump_detail *detail)
 {
 	/*
 	 * Outside of a panic context the pollers will continue to run,
 	 * so we don't need to do any special flushing.
 	 */
-	if (reason != KMSG_DUMP_PANIC)
+	if (detail->reason != KMSG_DUMP_PANIC)
 		return;
 
 	opal_flush_console(0);
diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
index 4382cf02a6d1..419021175272 100644
--- a/arch/um/kernel/kmsg_dump.c
+++ b/arch/um/kernel/kmsg_dump.c
@@ -8,7 +8,7 @@ 
 #include <os.h>
 
 static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
-				enum kmsg_dump_reason reason)
+				struct kmsg_dump_detail *detail)
 {
 	static struct kmsg_dump_iter iter;
 	static DEFINE_SPINLOCK(lock);
diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
index 948aed00595e..8794c7f6c0ee 100644
--- a/drivers/gpu/drm/drm_panic.c
+++ b/drivers/gpu/drm/drm_panic.c
@@ -655,11 +655,11 @@  static struct drm_plane *to_drm_plane(struct kmsg_dumper *kd)
 	return container_of(kd, struct drm_plane, kmsg_panic);
 }
 
-static void drm_panic(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason)
+static void drm_panic(struct kmsg_dumper *dumper, struct kmsg_dump_detail *detail)
 {
 	struct drm_plane *plane = to_drm_plane(dumper);
 
-	if (reason == KMSG_DUMP_PANIC)
+	if (detail->reason == KMSG_DUMP_PANIC)
 		draw_panic_plane(plane);
 }
 
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 9c452bfbd571..7a35c82976e0 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -207,13 +207,13 @@  static int hv_die_panic_notify_crash(struct notifier_block *self,
  * buffer and call into Hyper-V to transfer the data.
  */
 static void hv_kmsg_dump(struct kmsg_dumper *dumper,
-			 enum kmsg_dump_reason reason)
+			 struct kmsg_dump_detail *detail)
 {
 	struct kmsg_dump_iter iter;
 	size_t bytes_written;
 
 	/* We are only interested in panics. */
-	if (reason != KMSG_DUMP_PANIC || !sysctl_record_panic_msg)
+	if (detail->reason != KMSG_DUMP_PANIC || !sysctl_record_panic_msg)
 		return;
 
 	/*
diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
index 2f11585b5613..86d49db9196d 100644
--- a/drivers/mtd/mtdoops.c
+++ b/drivers/mtd/mtdoops.c
@@ -298,7 +298,7 @@  static void find_next_position(struct mtdoops_context *cxt)
 }
 
 static void mtdoops_do_dump(struct kmsg_dumper *dumper,
-			    enum kmsg_dump_reason reason)
+			    struct kmsg_dump_detail *detail)
 {
 	struct mtdoops_context *cxt = container_of(dumper,
 			struct mtdoops_context, dump);
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 3497ede88aa0..9c6b7c97fa3c 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -275,7 +275,7 @@  void pstore_record_init(struct pstore_record *record,
  * end of the buffer.
  */
 static void pstore_dump(struct kmsg_dumper *dumper,
-			enum kmsg_dump_reason reason)
+			struct kmsg_dump_detail *detail)
 {
 	struct kmsg_dump_iter iter;
 	unsigned long	total = 0;
@@ -285,9 +285,9 @@  static void pstore_dump(struct kmsg_dumper *dumper,
 	int		saved_ret = 0;
 	int		ret;
 
-	why = kmsg_dump_reason_str(reason);
+	why = kmsg_dump_reason_str(detail->reason);
 
-	if (pstore_cannot_block_path(reason)) {
+	if (pstore_cannot_block_path(detail->reason)) {
 		if (!spin_trylock_irqsave(&psinfo->buf_lock, flags)) {
 			pr_err("dump skipped in %s path because of concurrent dump\n",
 					in_nmi() ? "NMI" : why);
@@ -311,7 +311,7 @@  static void pstore_dump(struct kmsg_dumper *dumper,
 		pstore_record_init(&record, psinfo);
 		record.type = PSTORE_TYPE_DMESG;
 		record.count = oopscount;
-		record.reason = reason;
+		record.reason = detail->reason;
 		record.part = part;
 		record.buf = psinfo->buf;
 
@@ -352,7 +352,7 @@  static void pstore_dump(struct kmsg_dumper *dumper,
 		}
 
 		ret = psinfo->write(&record);
-		if (ret == 0 && reason == KMSG_DUMP_OOPS) {
+		if (ret == 0 && detail->reason == KMSG_DUMP_OOPS) {
 			pstore_new_entry = 1;
 			pstore_timer_kick();
 		} else {
diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
index 906521c2329c..65f5a47727bc 100644
--- a/include/linux/kmsg_dump.h
+++ b/include/linux/kmsg_dump.h
@@ -39,6 +39,17 @@  struct kmsg_dump_iter {
 	u64	next_seq;
 };
 
+/**
+ *struct kmsg_dump_detail - kernel crash detail
+ * @reason: reason for the crash, see kmsg_dump_reason.
+ * @description: optional short string, to provide additional information.
+ */
+
+struct kmsg_dump_detail {
+	enum kmsg_dump_reason reason;
+	const char *description;
+};
+
 /**
  * struct kmsg_dumper - kernel crash message dumper structure
  * @list:	Entry in the dumper list (private)
@@ -49,13 +60,13 @@  struct kmsg_dump_iter {
  */
 struct kmsg_dumper {
 	struct list_head list;
-	void (*dump)(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason);
+	void (*dump)(struct kmsg_dumper *dumper, struct kmsg_dump_detail *detail);
 	enum kmsg_dump_reason max_reason;
 	bool registered;
 };
 
 #ifdef CONFIG_PRINTK
-void kmsg_dump(enum kmsg_dump_reason reason);
+void kmsg_dump_desc(enum kmsg_dump_reason reason, const char *desc);
 
 bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,
 			char *line, size_t size, size_t *len);
@@ -71,7 +82,7 @@  int kmsg_dump_unregister(struct kmsg_dumper *dumper);
 
 const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason);
 #else
-static inline void kmsg_dump(enum kmsg_dump_reason reason)
+static inline void kmsg_dump_desc(enum kmsg_dump_reason reason, const char *desc)
 {
 }
 
@@ -107,4 +118,9 @@  static inline const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason)
 }
 #endif
 
+static inline void kmsg_dump(enum kmsg_dump_reason reason)
+{
+	kmsg_dump_desc(reason, NULL);
+}
+
 #endif /* _LINUX_KMSG_DUMP_H */
diff --git a/kernel/panic.c b/kernel/panic.c
index 0843a275531a..0a8b29c44f3c 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -378,7 +378,7 @@  void panic(const char *fmt, ...)
 
 	panic_print_sys_info(false);
 
-	kmsg_dump(KMSG_DUMP_PANIC);
+	kmsg_dump_desc(KMSG_DUMP_PANIC, buf);
 
 	/*
 	 * If you doubt kdump always works fine in any situation,
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 5dcc05e1aa56..19bc414be5f0 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -4272,16 +4272,21 @@  const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason)
 EXPORT_SYMBOL_GPL(kmsg_dump_reason_str);
 
 /**
- * kmsg_dump - dump kernel log to kernel message dumpers.
+ * kmsg_dump_desc - dump kernel log to kernel message dumpers.
  * @reason: the reason (oops, panic etc) for dumping
+ * @desc: a short string to describe what caused the panic or oops. Can be NULL
+ * if no additional description is available.
  *
  * Call each of the registered dumper's dump() callback, which can
  * retrieve the kmsg records with kmsg_dump_get_line() or
  * kmsg_dump_get_buffer().
  */
-void kmsg_dump(enum kmsg_dump_reason reason)
+void kmsg_dump_desc(enum kmsg_dump_reason reason, const char *desc)
 {
 	struct kmsg_dumper *dumper;
+	struct kmsg_dump_detail detail = {
+		.reason = reason,
+		.description = desc};
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(dumper, &dump_list, list) {
@@ -4299,7 +4304,7 @@  void kmsg_dump(enum kmsg_dump_reason reason)
 			continue;
 
 		/* invoke dumper which will iterate over records */
-		dumper->dump(dumper, reason);
+		dumper->dump(dumper, &detail);
 	}
 	rcu_read_unlock();
 }