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coredump: kill mm->core_done

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Now that we have core_state->dumper list we can use it to wake up the
sub-threads waiting for the coredump completion.

This uglifies the code and .text grows by 47 bytes, but otoh mm_struct
lessens by sizeof(struct completion).  Also, with this change we can
decouple exit_mm() from the coredumping code.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2008-07-25 01:47:46 -07:00 committed by Linus Torvalds
parent 182c515fd2
commit a94e2d408e
3 changed files with 30 additions and 7 deletions
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25
fs/exec.c
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@ -1602,7 +1602,6 @@ static int coredump_wait(int exit_code, struct core_state *core_state)
struct completion *vfork_done;
int core_waiters;
init_completion(&mm->core_done);
init_completion(&core_state->startup);
core_state->dumper.task = tsk;
core_state->dumper.next = NULL;
@ -1628,6 +1627,27 @@ fail:
return core_waiters;
}
static void coredump_finish(struct mm_struct *mm)
{
struct core_thread *curr, *next;
struct task_struct *task;
next = mm->core_state->dumper.next;
while ((curr = next) != NULL) {
next = curr->next;
task = curr->task;
/*
* see exit_mm(), curr->task must not see
* ->task == NULL before we read ->next.
*/
smp_mb();
curr->task = NULL;
wake_up_process(task);
}
mm->core_state = NULL;
}
/*
* set_dumpable converts traditional three-value dumpable to two flags and
* stores them into mm->flags. It modifies lower two bits of mm->flags, but
@ -1812,8 +1832,7 @@ fail_unlock:
argv_free(helper_argv);
current->fsuid = fsuid;
complete_all(&mm->core_done);
mm->core_state = NULL;
coredump_finish(mm);
fail:
return retval;
}

4
include/linux/mm_types.h
View File

@ -229,9 +229,7 @@ struct mm_struct {
unsigned long flags; /* Must use atomic bitops to access the bits */
/* coredumping support */
struct core_state *core_state;
struct completion core_done;
struct core_state *core_state; /* coredumping support */
/* aio bits */
rwlock_t ioctx_list_lock; /* aio lock */

8
kernel/exit.c
View File

@ -691,7 +691,13 @@ static void exit_mm(struct task_struct * tsk)
if (atomic_dec_and_test(&core_state->nr_threads))
complete(&core_state->startup);
wait_for_completion(&mm->core_done);
for (;;) {
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
if (!self.task) /* see coredump_finish() */
break;
schedule();
}
__set_task_state(tsk, TASK_RUNNING);
down_read(&mm->mmap_sem);
}
atomic_inc(&mm->mm_count);