• J
    x86_64: fix misplaced `continue' in mce.c · 4f84e4be
    Joshua Wise 提交于
    Background:
      When a userspace application wants to know about machine check events, it
      opens /dev/mcelog and does a read(). Usually, we found that this interface
      works well, but in some cases, when the system was taking large numbers of
      machine check exceptions, the read() would hang. The system would output a
      soft-lockup warning, and the daemon reading from /dev/mcelog would suck up
      as much of a single CPU as it could spinning in system space.
    
    Description:
      This patch fixes this bug. In particular, there was a "continue" inside a
      timeout loop that presumably was intended to break out of the outer loop,
      but instead caused the inner loop to continue. This patch also makes the
      condition for the break-out a little more evident by changing a
      !time_before to a time_after_eq.
    
    Result:
      The read() no longer hangs in this test case.
    
    Testing:
      On my system, I could replicate the bug with the following command:
        # for i in `seq 15000`; do ./inject_sbe.sh; done
      where inject_sbe.sh contains commands to inject a single-bit error into the
      next memory write transaction.
    
    Patch:
      This patch is against git f1518a08.
    Signed-off-by: NJoshua Wise <jwise@google.com>
    Signed-off-by: NTim Hockin <thockin@google.com>
    Cc: Andi Kleen <ak@suse.de>
    Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    4f84e4be
mce.c 18.4 KB