From: Pavel Andrianov <andrianov@ispras.ru>
To: Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>,
Lars-Peter Clausen <lars@metafoo.de>,
Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
Alexander Koch <mail@alexanderkoch.net>,
Vaishali Thakkar <vaishali.thakkar@oracle.com>,
ldv-project@linuxtesting.org
Subject: A potential bug in drivers/iio/light/opt3001.ko
Date: Wed, 31 Aug 2016 13:23:39 +0300 [thread overview]
Message-ID: <e5806302-9d1b-b262-766a-e64ca9a0159c@ispras.ru> (raw)
Hi!
There is a bug in drivers/iio/light/opt3001.ko. Regard such case:
Thread 1 Thread 2
-> opt3001_read_raw
-> mutex_lock(&opt->lock)
-> opt3001_get_lux()
..
->i2c_smbus_write_word_swapped()
Now an interrupt comes
-> opt3001_irq
-> mutex_lock(&opt->lock)
This is a deadlock, as the flag ok_to_ignore_lock has not been set yet.
Regard another case:
Thread 1 Thread 2
-> opt3001_read_raw
-> mutex_lock(&opt->lock)
-> opt3001_get_lux()
..
-> i2c_smbus_write_word_swapped()
opt->ok_to_ignore_lock = true;
Now an interrupt comes
-> opt3001_irq
..
opt->result_ready = true
wake_up()
opt->result_ready = false;
wait_event_timeout()
In this case the first thread misses the result and waits until timeout
expires.
--
Pavel Andrianov
Linux Verification Center, ISPRAS
web: http://linuxtesting.org
e-mail: andrianov@ispras.ru
next reply other threads:[~2016-08-31 10:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-31 10:23 Pavel Andrianov [this message]
2016-09-03 16:38 ` Jonathan Cameron
2016-09-05 14:15 ` Pavel Andrianov
2016-09-05 20:04 ` Jonathan Cameron
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