coredump: kill mm->core_done
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>
diff --git a/fs/exec.c b/fs/exec.c
index fe2873b..bff43ae 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1602,7 +1602,6 @@
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 @@
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 @@
argv_free(helper_argv);
current->fsuid = fsuid;
- complete_all(&mm->core_done);
- mm->core_state = NULL;
+ coredump_finish(mm);
fail:
return retval;
}
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 4d0d0ab..746f975 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -229,9 +229,7 @@
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 */
diff --git a/kernel/exit.c b/kernel/exit.c
index b66f0d5..8a4d4d1 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -691,7 +691,13 @@
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);