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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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2b97e2201e
KERNEL_VERSION: 2.6.37
common.c in function ssize_t si470x_fops_read.
1. First mutex_lock on &radio->lock in line 441
2. Second in line 462
I think that mutex in line 462 is not needed.
433static ssize_t si470x_fops_read(struct file *file, char __user *buf,
434 size_t count, loff_t *ppos)
435{
....
441 mutex_lock(&radio->lock);
442 if ((radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS) == 0)
443 si470x_rds_on(radio);
444
445 /* block if no new data available */
446 while (radio->wr_index == radio->rd_index) {
447 if (file->f_flags & O_NONBLOCK) {
448 retval = -EWOULDBLOCK;
449 goto done;
450 }
451 if (wait_event_interruptible(radio->read_queue,
452 radio->wr_index != radio->rd_index) < 0) {
453 retval = -EINTR;
454 goto done;
455 }
456 }
457
458 /* calculate block count from byte count */
459 count /= 3;
460
461 /* copy RDS block out of internal buffer and to user buffer */
462 mutex_lock(&radio->lock);
Found by Linux Device Drivers Verification Project
Remove second mutex.
Signed-off-by: Alexander Strakh <strakh@ispras.ru>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>