posix-cpu-timers: avoid "task->signal != NULL" checks

Preparation to make task->signal immutable, no functional changes.

posix-cpu-timers.c checks task->signal != NULL to ensure this task is
alive and didn't pass __exit_signal().  This is correct but we are going
to change the lifetime rules for ->signal and never reset this pointer.

Change the code to check ->sighand instead, it doesn't matter which
pointer we check under tasklist, they both are cleared simultaneously.

As Roland pointed out, some of these changes are not strictly needed and
probably it makes sense to revert them later, when ->signal will be pinned
to task_struct.  But this patch tries to ensure the subsequent changes in
fork/exit can't make any visible impact on posix cpu timers.

Signed-off-by: Oleg Nesterov <[email protected]>
Cc: Fenghua Yu <[email protected]>
Acked-by: Roland McGrath <[email protected]>
Cc: Stanislaw Gruszka <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions