linux-kernel - Re: [Linaro-mm-sig] [PATCH] dma-buf/sw-sync: don't enable IRQ from sync_print

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Message-ID: <0204a827-ca88-4cb6-839b-f4a637bcbf71@I-love.SAKURA.ne.jp>
Date: Fri, 24 May 2024 22:26:20 +0900
From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To: Christian König <ckoenig.leichtzumerken@...il.com>,
        syzbot <syzbot+a225ee3df7e7f9372dbe@...kaller.appspotmail.com>,
        syzkaller-bugs@...glegroups.com,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Gustavo Padovan <gustavo@...ovan.org>,
        Christian Konig <christian.koenig@....com>,
        Sean Paul
 <seanpaul@...omium.org>,
        Chris Wilson <chris@...is-wilson.co.uk>
Cc: linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linaro-mm-sig@...ts.linaro.org, dri-devel@...ts.freedesktop.org
Subject: Re: [Linaro-mm-sig] [PATCH] dma-buf/sw-sync: don't enable IRQ from
 sync_print_obj()

On 2024/05/07 22:09, Christian König wrote:
> Am 05.05.24 um 16:08 schrieb Tetsuo Handa:
>> Since commit a6aa8fca4d79 ("dma-buf/sw-sync: Reduce irqsave/irqrestore from
>> known context") by error replaced spin_unlock_irqrestore() with
>> spin_unlock_irq() for both sync_debugfs_show() and sync_print_obj() despite
>> sync_print_obj() is called from sync_debugfs_show(), lockdep complains
>> inconsistent lock state warning.
>>
>> Use plain spin_{lock,unlock}() for sync_print_obj(), for
>> sync_debugfs_show() is already using spin_{lock,unlock}_irq().
>>
>> Reported-by: syzbot <syzbot+a225ee3df7e7f9372dbe@...kaller.appspotmail.com>
>> Closes: https://syzkaller.appspot.com/bug?extid=a225ee3df7e7f9372dbe
>> Fixes: a6aa8fca4d79 ("dma-buf/sw-sync: Reduce irqsave/irqrestore from known context")
>> Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> 
> Reviewed-by: Christian König <christian.koenig@....com>

Thank you. Who can take this patch?

> 
>> ---
>>   drivers/dma-buf/sync_debug.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
>> index 101394f16930..237bce21d1e7 100644
>> --- a/drivers/dma-buf/sync_debug.c
>> +++ b/drivers/dma-buf/sync_debug.c
>> @@ -110,12 +110,12 @@ static void sync_print_obj(struct seq_file *s, struct sync_timeline *obj)
>>         seq_printf(s, "%s: %d\n", obj->name, obj->value);
>>   -    spin_lock_irq(&obj->lock);
>> +    spin_lock(&obj->lock); /* Caller already disabled IRQ. */
>>       list_for_each(pos, &obj->pt_list) {
>>           struct sync_pt *pt = container_of(pos, struct sync_pt, link);
>>           sync_print_fence(s, &pt->base, false);
>>       }
>> -    spin_unlock_irq(&obj->lock);
>> +    spin_unlock(&obj->lock);
>>   }
>>     static void sync_print_sync_file(struct seq_file *s,
>