Make /dev/zero reads interruptible by signals

This helps with bad latencies for large reads from /dev/zero, but might
conceivably break some application that "knows" that a read of /dev/zero
cannot return early.  So do this early in the merge window to give us
maximal test coverage, even if the patch is totally trivial.

Obviously, no well-behaved application should ever depend on the read
being uninterruptible, but hey, bugs happen.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 3 deletions

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 65e12bca657c..f96d0bef855e 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -694,9 +694,8 @@ static ssize_t read_zero(struct file * file, char __user * buf,
                 written += chunk - unwritten;
                 if (unwritten)
                         break;
-                /* Consider changing this to just 'signal_pending()' with lots of testing */
-                if (fatal_signal_pending(current))
-                        return written ? written : -EINTR;
+                if (signal_pending(current))
+                        return written ? written : -ERESTARTSYS;
                 buf += chunk;
                 count -= chunk;
                 cond_resched();