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SubjectRe: [PATCH] UBI: Fix possible deadlock in erase_worker()
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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?

--
Best Regards,
Artem Bityutskiy



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