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ieee1394: raw1394: make write() thread-safe 

Application programs should use a libraw1394 handle only in a single
thread.  The raw1394 driver was apparently relying on this, because it
did nothing to protect its fi->state variable from corruption due to
concurrent accesses.

We now serialize the fi->state accesses.  This affects the write() path.
We re-use the state_mutex which was introduced to protect fi->iso_state
accesses in the ioctl() path.  These paths and accesses are independent
of each other, hence separate mutexes could be used.  But I don't see
much benefit in that.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Stefan Richter 2008-08-16 00:15:16 +02:00
parent ddfb908d3f
commit f22e52b89e
1 changed files with 4 additions and 0 deletions
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4
drivers/ieee1394/raw1394.c
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@ -2268,6 +2268,8 @@ static ssize_t raw1394_write(struct file *file, const char __user * buffer,
return -EFAULT;
}
mutex_lock(&fi->state_mutex);
switch (fi->state) {
case opened:
retval = state_opened(fi, req);
@ -2282,6 +2284,8 @@ static ssize_t raw1394_write(struct file *file, const char __user * buffer,
break;
}
mutex_unlock(&fi->state_mutex);
if (retval < 0) {
free_pending_request(req);
} else {