From: Richard Weinberger <richard@nod.at>
To: dedekind1@gmail.com
Cc: dwmw2@infradead.org, computersforpeace@gmail.com,
linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] UBI: Fix possible deadlock in erase_worker()
Date: Fri, 19 Sep 2014 11:46:21 +0200 [thread overview]
Message-ID: <541BFB6D.3040903@nod.at> (raw)
In-Reply-To: <1410946526.28850.120.camel@sauron.fi.intel.com>
Am 17.09.2014 11:35, schrieb Artem Bityutskiy:
> On Tue, 2014-09-16 at 09:48 +0200, Richard Weinberger wrote:
>> If sync_erase() failes with EINTR, ENOMEM, EAGAIN or
>> EBUSY erase_worker() re-schedules the failed work.
>> This will lead to a deadlock because erase_worker() is called
>> with work_sem held in read mode. And schedule_erase() will take
>> this lock again.
>
> There is this code snippet:
>
> ubi_err("failed to erase PEB %d, error %d", pnum, err);
> kfree(wl_wrk);
>
> if (err == -EINTR || err == -ENOMEM || err == -EAGAIN ||
> err == -EBUSY) {
> int err1;
>
> /* Re-schedule the LEB for erasure */
> err1 = schedule_erase(ubi, e, vol_id, lnum, 0);
> if (err1) {
> err = err1;
> goto out_ro;
> }
> return err;
> }
>
> How about move 'kfree(wl_wrk)' down, and execute
>
> __schedule_ubi_work(ubi, wl_wrk)
>
> inside the 'if' clause instead? The fix would seem to be more elegant
> then.
>
> Hmm?
Yes, that would work too.
Or we apply "[PATCH 1/2] UBI: Call worker functions without work_sem held". :)
Thanks,
//richard
next prev parent reply other threads:[~2014-09-19 9:46 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-16 7:48 [PATCH] UBI: Fix possible deadlock in erase_worker() Richard Weinberger
2014-09-17 8:28 ` Artem Bityutskiy
2014-09-17 8:40 ` Richard Weinberger
2014-09-17 8:43 ` Artem Bityutskiy
2014-09-17 9:35 ` Artem Bityutskiy
2014-09-19 9:46 ` Richard Weinberger [this message]
2014-09-19 10:47 ` Artem Bityutskiy
2014-09-19 11:01 ` Richard Weinberger
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