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Commit 1b9f2372 authored by Richard Cochran's avatar Richard Cochran Committed by Thomas Gleixner
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posix-clock: Fix return code on the poll method's error path 



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.com


Cc: stable@vger.kernel.org
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 74bf8efb

kernel/time/posix-clock.c

+2 −2
Original line number Diff line number Diff line
@@ -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);