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author | Oleg Nesterov <oleg@redhat.com> | 2013-04-30 22:28:12 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-05-01 00:04:06 (GMT) |
commit | 6cd8f0acae3420afce37bf51a9ff8c2c20342af5 (patch) | |
tree | 38478d4eb5b1c2d911c865c088a79edf2ebcea77 /crypto/sha512_generic.c | |
parent | 403bad72b67d8b3f5a0240af5023adfa48132a65 (diff) | |
download | linux-fsl-qoriq-6cd8f0acae3420afce37bf51a9ff8c2c20342af5.tar.xz |
coredump: ensure that SIGKILL always kills the dumping thread
prepare_signal() blesses SIGKILL sent to the dumping process but this
signal can be "lost" anyway. The problems is, complete_signal() sees
SIGNAL_GROUP_EXIT and skips the "kill them all" logic. And even if the
dumping process is single-threaded (so the target is always "correct"),
the group-wide SIGKILL is not recorded in task->pending and thus
__fatal_signal_pending() won't be true. A multi-threaded case has even
more problems.
And even ignoring all technical details, SIGNAL_GROUP_EXIT doesn't look
right to me. This coredumping process is not exiting yet, it can do a lot
of work dumping the core.
With this patch the dumping process doesn't have SIGNAL_GROUP_EXIT, we set
signal->group_exit_task instead. This makes signal_group_exit() true and
thus this should equally close the races with exit/exec/stop but allows to
kill the dumping thread reliably.
Notes:
- It is not clear what should we do with ->group_exit_code
if the dumper was killed, see the next change.
- we need more (hopefully straightforward) changes to ensure
that SIGKILL actually interrupts the coredump. Basically we
need to check __fatal_signal_pending() in dump_write() and
dump_seek().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Neil Horman <nhorman@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'crypto/sha512_generic.c')
0 files changed, 0 insertions, 0 deletions