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| author | Francois Romieu <romieu@fr.zoreil.com> | 2017-03-11 19:41:36 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-03-13 15:37:29 -0700 |
| commit | c55fa3cccbc2c672e7f118be8f7484e53a8e9e77 (patch) | |
| tree | 06147d1603162f9c84a5f2970db5884c2090aba8 /net/atm | |
| parent | be086e7c53f1fac51eed14523b28f2214b548dd2 (diff) | |
| download | linux-c55fa3cccbc2c672e7f118be8f7484e53a8e9e77.tar.gz | |
atm: remove an unnecessary loop
Andrey reported this kernel warning:
WARNING: CPU: 0 PID: 4114 at kernel/sched/core.c:7737 __might_sleep+0x149/0x1a0
do not call blocking ops when !TASK_RUNNING; state=1 set at
[<ffffffff813fcb22>] prepare_to_wait+0x182/0x530
The deeply nested alloc_skb is a problem.
Diagnosis: nesting is wrong. It makes zero sense. Fix it and the
implicit task state change problem automagically goes away.
alloc_skb() does not need to be in the "while" loop.
alloc_skb() does not need to be in the {prepare_to_wait/add_wait_queue ...
finish_wait/remove_wait_queue} block.
I claim that:
- alloc_tx() should only perform the "wait_for_decent_tx_drain" part
- alloc_skb() ought to be done directly in vcc_sendmsg
- alloc_skb() failure can be handled gracefully in vcc_sendmsg
- alloc_skb() may use a (m->msg_flags & MSG_DONTWAIT) dependent
GFP_{KERNEL / ATOMIC} flag
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-and-Tested-by: Chas Williams <3chas3@gmail.com>
Signed-off-by: Chas Williams <3chas3@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/atm')
| -rw-r--r-- | net/atm/common.c | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/net/atm/common.c b/net/atm/common.c index 9613381f5db0..f06422f4108d 100644 --- a/net/atm/common.c +++ b/net/atm/common.c @@ -62,21 +62,16 @@ static void vcc_remove_socket(struct sock *sk) write_unlock_irq(&vcc_sklist_lock); } -static struct sk_buff *alloc_tx(struct atm_vcc *vcc, unsigned int size) +static bool vcc_tx_ready(struct atm_vcc *vcc, unsigned int size) { - struct sk_buff *skb; struct sock *sk = sk_atm(vcc); if (sk_wmem_alloc_get(sk) && !atm_may_send(vcc, size)) { pr_debug("Sorry: wmem_alloc = %d, size = %d, sndbuf = %d\n", sk_wmem_alloc_get(sk), size, sk->sk_sndbuf); - return NULL; + return false; } - while (!(skb = alloc_skb(size, GFP_KERNEL))) - schedule(); - pr_debug("%d += %d\n", sk_wmem_alloc_get(sk), skb->truesize); - atomic_add(skb->truesize, &sk->sk_wmem_alloc); - return skb; + return true; } static void vcc_sock_destruct(struct sock *sk) @@ -606,7 +601,7 @@ int vcc_sendmsg(struct socket *sock, struct msghdr *m, size_t size) eff = (size+3) & ~3; /* align to word boundary */ prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE); error = 0; - while (!(skb = alloc_tx(vcc, eff))) { + while (!vcc_tx_ready(vcc, eff)) { if (m->msg_flags & MSG_DONTWAIT) { error = -EAGAIN; break; @@ -628,6 +623,15 @@ int vcc_sendmsg(struct socket *sock, struct msghdr *m, size_t size) finish_wait(sk_sleep(sk), &wait); if (error) goto out; + + skb = alloc_skb(eff, GFP_KERNEL); + if (!skb) { + error = -ENOMEM; + goto out; + } + pr_debug("%d += %d\n", sk_wmem_alloc_get(sk), skb->truesize); + atomic_add(skb->truesize, &sk->sk_wmem_alloc); + skb->dev = NULL; /* for paths shared with net_device interfaces */ ATM_SKB(skb)->atm_options = vcc->atm_options; if (!copy_from_iter_full(skb_put(skb, size), size, &m->msg_iter)) { |