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atm/svc: Fix blocking in wait loop

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One should not call blocking primitives inside a wait loop, since both
require task_struct::state to sleep, so the inner will destroy the
outer state.

sigd_enq() will possibly sleep for alloc_skb().  Move sigd_enq() before
prepare_to_wait() to avoid sleeping while waiting interruptibly.  You do
not actually need to call sigd_enq() after the initial prepare_to_wait()
because we test the termination condition before calling schedule().

Based on suggestions from Peter Zijlstra.

Signed-off-by: Chas Williams <chas@cmf.n4rl.navy.mil>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
chas williams - CONTRACTOR 2014-08-12 08:12:26 -04:00 committed by David S. Miller
parent 10545937e8
commit de713b5794
1 changed files with 32 additions and 28 deletions
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60
net/atm/svc.c
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@ -50,12 +50,12 @@ static void svc_disconnect(struct atm_vcc *vcc)
pr_debug("%p\n", vcc);
if (test_bit(ATM_VF_REGIS, &vcc->flags)) {
prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
sigd_enq(vcc, as_close, NULL, NULL, NULL);
while (!test_bit(ATM_VF_RELEASED, &vcc->flags) && sigd) {
for (;;) {
prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
if (test_bit(ATM_VF_RELEASED, &vcc->flags) || !sigd)
break;
schedule();
prepare_to_wait(sk_sleep(sk), &wait,
TASK_UNINTERRUPTIBLE);
}
finish_wait(sk_sleep(sk), &wait);
}
@ -126,11 +126,12 @@ static int svc_bind(struct socket *sock, struct sockaddr *sockaddr,
}
vcc->local = *addr;
set_bit(ATM_VF_WAITING, &vcc->flags);
prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
sigd_enq(vcc, as_bind, NULL, NULL, &vcc->local);
while (test_bit(ATM_VF_WAITING, &vcc->flags) && sigd) {
schedule();
for (;;) {
prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
if (!test_bit(ATM_VF_WAITING, &vcc->flags) || !sigd)
break;
schedule();
}
finish_wait(sk_sleep(sk), &wait);
clear_bit(ATM_VF_REGIS, &vcc->flags); /* doesn't count */
@ -202,15 +203,14 @@ static int svc_connect(struct socket *sock, struct sockaddr *sockaddr,
}
vcc->remote = *addr;
set_bit(ATM_VF_WAITING, &vcc->flags);
prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
sigd_enq(vcc, as_connect, NULL, NULL, &vcc->remote);
if (flags & O_NONBLOCK) {
finish_wait(sk_sleep(sk), &wait);
sock->state = SS_CONNECTING;
error = -EINPROGRESS;
goto out;
}
error = 0;
prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
while (test_bit(ATM_VF_WAITING, &vcc->flags) && sigd) {
schedule();
if (!signal_pending(current)) {
@ -297,11 +297,12 @@ static int svc_listen(struct socket *sock, int backlog)
goto out;
}
set_bit(ATM_VF_WAITING, &vcc->flags);
prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
sigd_enq(vcc, as_listen, NULL, NULL, &vcc->local);
while (test_bit(ATM_VF_WAITING, &vcc->flags) && sigd) {
schedule();
for (;;) {
prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
if (!test_bit(ATM_VF_WAITING, &vcc->flags) || !sigd)
break;
schedule();
}
finish_wait(sk_sleep(sk), &wait);
if (!sigd) {
@ -387,15 +388,15 @@ static int svc_accept(struct socket *sock, struct socket *newsock, int flags)
}
/* wait should be short, so we ignore the non-blocking flag */
set_bit(ATM_VF_WAITING, &new_vcc->flags);
prepare_to_wait(sk_sleep(sk_atm(new_vcc)), &wait,
TASK_UNINTERRUPTIBLE);
sigd_enq(new_vcc, as_accept, old_vcc, NULL, NULL);
while (test_bit(ATM_VF_WAITING, &new_vcc->flags) && sigd) {
for (;;) {
prepare_to_wait(sk_sleep(sk_atm(new_vcc)), &wait,
TASK_UNINTERRUPTIBLE);
if (!test_bit(ATM_VF_WAITING, &new_vcc->flags) || !sigd)
break;
release_sock(sk);
schedule();
lock_sock(sk);
prepare_to_wait(sk_sleep(sk_atm(new_vcc)), &wait,
TASK_UNINTERRUPTIBLE);
}
finish_wait(sk_sleep(sk_atm(new_vcc)), &wait);
if (!sigd) {
@ -433,12 +434,14 @@ int svc_change_qos(struct atm_vcc *vcc, struct atm_qos *qos)
DEFINE_WAIT(wait);
set_bit(ATM_VF_WAITING, &vcc->flags);
prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
sigd_enq2(vcc, as_modify, NULL, NULL, &vcc->local, qos, 0);
while (test_bit(ATM_VF_WAITING, &vcc->flags) &&
!test_bit(ATM_VF_RELEASED, &vcc->flags) && sigd) {
schedule();
for (;;) {
prepare_to_wait(sk_sleep(sk), &wait, TASK_UNINTERRUPTIBLE);
if (!test_bit(ATM_VF_WAITING, &vcc->flags) ||
test_bit(ATM_VF_RELEASED, &vcc->flags) || !sigd) {
break;
}
schedule();
}
finish_wait(sk_sleep(sk), &wait);
if (!sigd)
@ -529,18 +532,18 @@ static int svc_addparty(struct socket *sock, struct sockaddr *sockaddr,
lock_sock(sk);
set_bit(ATM_VF_WAITING, &vcc->flags);
prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
sigd_enq(vcc, as_addparty, NULL, NULL,
(struct sockaddr_atmsvc *) sockaddr);
if (flags & O_NONBLOCK) {
finish_wait(sk_sleep(sk), &wait);
error = -EINPROGRESS;
goto out;
}
pr_debug("added wait queue\n");
while (test_bit(ATM_VF_WAITING, &vcc->flags) && sigd) {
schedule();
for (;;) {
prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
if (!test_bit(ATM_VF_WAITING, &vcc->flags) || !sigd)
break;
schedule();
}
finish_wait(sk_sleep(sk), &wait);
error = xchg(&sk->sk_err_soft, 0);
@ -558,11 +561,12 @@ static int svc_dropparty(struct socket *sock, int ep_ref)
lock_sock(sk);
set_bit(ATM_VF_WAITING, &vcc->flags);
prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
sigd_enq2(vcc, as_dropparty, NULL, NULL, NULL, NULL, ep_ref);
while (test_bit(ATM_VF_WAITING, &vcc->flags) && sigd) {
schedule();
for (;;) {
prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
if (!test_bit(ATM_VF_WAITING, &vcc->flags) || !sigd)
break;
schedule();
}
finish_wait(sk_sleep(sk), &wait);
if (!sigd) {