[PATCH] iwlwifi: iwl-dbg: Use del_timer_sync() before freeing

[PATCH] iwlwifi: iwl-dbg: Use del_timer_sync() before freeing

[Guenter Roeck]

In Chrome OS, a large number of crashes is observed due to corrupted timer
lists. Steven Rostedt pointed out that this usually happens when a timer
is freed while still active, and that the problem is often triggered
by code calling del_timer() instead of del_timer_sync() just before
freeing.

Steven also identified the iwlwifi driver as one of the possible culprits
since it does exactly that.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Gregory Greenman <gregory.greenman@intel.com>
Fixes: 60e8abd9d3e91 ("iwlwifi: dbg_ini: add periodic trigger new API support")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v1 (from RFC):
    Removed Shahar S Matityahu from Cc: and added Gregory Greenman.
    No functional change.

I thought about the need to add a mutex to protect the timer list, but
I convinced myself that it is not necessary because the code adding
the timer list and the code removing it should never be never executed
in parallel.

 drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c b/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
index 866a33f49915..3237d4b528b5 100644
--- a/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
+++ b/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
@@ -371,7 +371,7 @@ void iwl_dbg_tlv_del_timers(struct iwl_trans *trans)
 	struct iwl_dbg_tlv_timer_node *node, *tmp;
 
 	list_for_each_entry_safe(node, tmp, timer_list, list) {
-		del_timer(&node->timer);
+		del_timer_sync(&node->timer);
 		list_del(&node->list);
 		kfree(node);
 	}
-- 
2.35.1

Re: [PATCH] iwlwifi: iwl-dbg: Use del_timer_sync() before freeing

[Greenman, Gregory]

On Mon, 2022-04-11 at 08:42 -0700, Guenter Roeck wrote:
> In Chrome OS, a large number of crashes is observed due to corrupted
> timer
> lists. Steven Rostedt pointed out that this usually happens when a
> timer
> is freed while still active, and that the problem is often triggered
> by code calling del_timer() instead of del_timer_sync() just before
> freeing.
> 
> Steven also identified the iwlwifi driver as one of the possible
> culprits
> since it does exactly that.
> 
> Reported-by: Steven Rostedt <rostedt@goodmis.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Johannes Berg <johannes.berg@intel.com>
> Cc: Gregory Greenman <gregory.greenman@intel.com>
> Fixes: 60e8abd9d3e91 ("iwlwifi: dbg_ini: add periodic trigger new API
> support")
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
> v1 (from RFC):
>     Removed Shahar S Matityahu from Cc: and added Gregory Greenman.
>     No functional change.
> 
> I thought about the need to add a mutex to protect the timer list,
> but
> I convinced myself that it is not necessary because the code adding
> the timer list and the code removing it should never be never
> executed
> in parallel.
> 
>  drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
> b/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
> index 866a33f49915..3237d4b528b5 100644
> --- a/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
> +++ b/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
> @@ -371,7 +371,7 @@ void iwl_dbg_tlv_del_timers(struct iwl_trans
> *trans)
>         struct iwl_dbg_tlv_timer_node *node, *tmp;
>  
>         list_for_each_entry_safe(node, tmp, timer_list, list) {
> -               del_timer(&node->timer);
> +               del_timer_sync(&node->timer);
>                 list_del(&node->list);
>                 kfree(node);
>         }

Hi Kalle,

Can you please pick it up to wireless-drivers for the next rc?
It is an important fix.
Luca has already assigned it to you in patchwork.

Thanks!

Acked-by: Gregory Greenman <gregory.greenman@intel.com>

Re: [PATCH] iwlwifi: iwl-dbg: Use del_timer_sync() before freeing

[Sedat Dilek]

On Wed, Apr 13, 2022 at 11:56 AM Greenman, Gregory
<gregory.greenman@intel.com> wrote:
>
>
> On Mon, 2022-04-11 at 08:42 -0700, Guenter Roeck wrote:
> > In Chrome OS, a large number of crashes is observed due to corrupted
> > timer
> > lists. Steven Rostedt pointed out that this usually happens when a
> > timer
> > is freed while still active, and that the problem is often triggered
> > by code calling del_timer() instead of del_timer_sync() just before
> > freeing.
> >
> > Steven also identified the iwlwifi driver as one of the possible
> > culprits
> > since it does exactly that.
> >
> > Reported-by: Steven Rostedt <rostedt@goodmis.org>
> > Cc: Steven Rostedt <rostedt@goodmis.org>
> > Cc: Johannes Berg <johannes.berg@intel.com>
> > Cc: Gregory Greenman <gregory.greenman@intel.com>
> > Fixes: 60e8abd9d3e91 ("iwlwifi: dbg_ini: add periodic trigger new API
> > support")
> > Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> > ---
> > v1 (from RFC):
> >     Removed Shahar S Matityahu from Cc: and added Gregory Greenman.
> >     No functional change.
> >
> > I thought about the need to add a mutex to protect the timer list,
> > but
> > I convinced myself that it is not necessary because the code adding
> > the timer list and the code removing it should never be never
> > executed
> > in parallel.
> >
> >  drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
> > b/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
> > index 866a33f49915..3237d4b528b5 100644
> > --- a/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
> > +++ b/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
> > @@ -371,7 +371,7 @@ void iwl_dbg_tlv_del_timers(struct iwl_trans
> > *trans)
> >         struct iwl_dbg_tlv_timer_node *node, *tmp;
> >
> >         list_for_each_entry_safe(node, tmp, timer_list, list) {
> > -               del_timer(&node->timer);
> > +               del_timer_sync(&node->timer);
> >                 list_del(&node->list);
> >                 kfree(node);
> >         }
>
> Hi Kalle,
>
> Can you please pick it up to wireless-drivers for the next rc?
> It is an important fix.
> Luca has already assigned it to you in patchwork.
>
> Thanks!
>
> Acked-by: Gregory Greenman <gregory.greenman@intel.com>

I have tested this on top of Linux v5.17.3-rc1.

Feel free to add my...

Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # Linux v5.17.3-rc1 and
Debian LLVM-14

- Sedat -

Re: [PATCH] iwlwifi: iwl-dbg: Use del_timer_sync() before freeing

[Kalle Valo]

Sedat Dilek <sedat.dilek@gmail.com> writes:

> On Wed, Apr 13, 2022 at 11:56 AM Greenman, Gregory
> <gregory.greenman@intel.com> wrote:
>>
>>
>> On Mon, 2022-04-11 at 08:42 -0700, Guenter Roeck wrote:
>> > In Chrome OS, a large number of crashes is observed due to corrupted
>> > timer
>> > lists. Steven Rostedt pointed out that this usually happens when a
>> > timer
>> > is freed while still active, and that the problem is often triggered
>> > by code calling del_timer() instead of del_timer_sync() just before
>> > freeing.
>> >
>> > Steven also identified the iwlwifi driver as one of the possible
>> > culprits
>> > since it does exactly that.
>> >
>> > Reported-by: Steven Rostedt <rostedt@goodmis.org>
>> > Cc: Steven Rostedt <rostedt@goodmis.org>
>> > Cc: Johannes Berg <johannes.berg@intel.com>
>> > Cc: Gregory Greenman <gregory.greenman@intel.com>
>> > Fixes: 60e8abd9d3e91 ("iwlwifi: dbg_ini: add periodic trigger new API
>> > support")
>> > Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>> > ---
>> > v1 (from RFC):
>> >     Removed Shahar S Matityahu from Cc: and added Gregory Greenman.
>> >     No functional change.
>> >
>> > I thought about the need to add a mutex to protect the timer list,
>> > but
>> > I convinced myself that it is not necessary because the code adding
>> > the timer list and the code removing it should never be never
>> > executed
>> > in parallel.
>> >
>> >  drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
>> > b/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
>> > index 866a33f49915..3237d4b528b5 100644
>> > --- a/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
>> > +++ b/drivers/net/wireless/intel/iwlwifi/iwl-dbg-tlv.c
>> > @@ -371,7 +371,7 @@ void iwl_dbg_tlv_del_timers(struct iwl_trans
>> > *trans)
>> >         struct iwl_dbg_tlv_timer_node *node, *tmp;
>> >
>> >         list_for_each_entry_safe(node, tmp, timer_list, list) {
>> > -               del_timer(&node->timer);
>> > +               del_timer_sync(&node->timer);
>> >                 list_del(&node->list);
>> >                 kfree(node);
>> >         }
>>
>> Hi Kalle,
>>
>> Can you please pick it up to wireless-drivers for the next rc?
>> It is an important fix.
>> Luca has already assigned it to you in patchwork.
>>
>> Thanks!
>>
>> Acked-by: Gregory Greenman <gregory.greenman@intel.com>
>
> I have tested this on top of Linux v5.17.3-rc1.
>
> Feel free to add my...
>
> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # Linux v5.17.3-rc1 and
> Debian LLVM-14

Please keep the Tested-by in one line, otherwise patchwork cannot parse
it correctly. I fixed this manually during commit.

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: iwlwifi: iwl-dbg: Use del_timer_sync() before freeing

[Kalle Valo]

Guenter Roeck <linux@roeck-us.net> wrote:

> In Chrome OS, a large number of crashes is observed due to corrupted timer
> lists. Steven Rostedt pointed out that this usually happens when a timer
> is freed while still active, and that the problem is often triggered
> by code calling del_timer() instead of del_timer_sync() just before
> freeing.
> 
> Steven also identified the iwlwifi driver as one of the possible culprits
> since it does exactly that.
> 
> Reported-by: Steven Rostedt <rostedt@goodmis.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Johannes Berg <johannes.berg@intel.com>
> Cc: Gregory Greenman <gregory.greenman@intel.com>
> Fixes: 60e8abd9d3e91 ("iwlwifi: dbg_ini: add periodic trigger new API support")
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> Acked-by: Gregory Greenman <gregory.greenman@intel.com>
> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # Linux v5.17.3-rc1 and Debian LLVM-14

Patch applied to wireless.git, thanks.

7635a1ad8d92 iwlwifi: iwl-dbg: Use del_timer_sync() before freeing

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20220411154210.1870008-1-linux@roeck-us.net/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches