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

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Message-ID: <0b04b587-77a4-4ac4-8b15-6cde0f0c5f5a@gmail.com>
Date: Mon, 27 May 2024 09:02:54 +0200
From: Christian König <ckoenig.leichtzumerken@...il.com>
To: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
 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()

Am 24.05.24 um 15:26 schrieb Tetsuo Handa:
> 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?

I pushed it to drm-misc-fixes.

Thanks,
Christian.

>
>>> ---
>>>    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,