Commit 2f0b10ce authored by Richard Cochran's avatar Richard Cochran Committed by Luis Henriques

posix-clock: Fix return code on the poll method's error path

commit 1b9f2372 upstream.

The posix_clock_poll function is supposed to return a bit mask of
POLLxxx values.  However, in case the hardware has disappeared (due to
hot plugging for example) this code returns -ENODEV in a futile
attempt to throw an error at the file descriptor level.  The kernel's
file_operations interface does not accept such error codes from the
poll method.  Instead, this function aught to return POLLERR.

The value -ENODEV does, in fact, contain the POLLERR bit (and almost
all the other POLLxxx bits as well), but only by chance.  This patch
fixes code to return a proper bit mask.

Credit goes to Markus Elfring for pointing out the suspicious
signed/unsigned mismatch.
Reported-by: default avatarMarkus Elfring <elfring@users.sourceforge.net>
igned-off-by: default avatarRichard Cochran <richardcochran@gmail.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Link: http://lkml.kernel.org/r/1450819198-17420-1-git-send-email-richardcochran@gmail.comSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent 48677726
......@@ -69,10 +69,10 @@ static ssize_t posix_clock_read(struct file *fp, char __user *buf,
static unsigned int posix_clock_poll(struct file *fp, poll_table *wait)
{
struct posix_clock *clk = get_posix_clock(fp);
int result = 0;
unsigned int result = 0;
if (!clk)
return -ENODEV;
return POLLERR;
if (clk->ops.poll)
result = clk->ops.poll(clk, fp, wait);
......
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