| Message ID | 20141029180734.GQ12706@worktop.programming.kicks-ass.net |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | David Miller |
| Headers | show |
On Wed, 29 Oct 2014, Peter Zijlstra wrote: > On Wed, Oct 29, 2014 at 04:56:20PM +0100, Sabrina Dubroca wrote: > > commit e22b886a8a43b ("sched/wait: Add might_sleep() checks") included > > in today's linux-next added a check that fires on e1000 with netpoll: > > > > > > BUG: sleeping function called from invalid context at kernel/irq/manage.c:104 > > in_atomic(): 1, irqs_disabled(): 1, pid: 1, name: systemd > > no locks held by systemd/1. > > irq event stamp: 10102965 > > hardirqs last enabled at (10102965): [<ffffffff810cbafd>] vprintk_emit+0x2dd/0x6a0 > > hardirqs last disabled at (10102964): [<ffffffff810cb897>] vprintk_emit+0x77/0x6a0 > > softirqs last enabled at (10102342): [<ffffffff810666aa>] __do_softirq+0x27a/0x6f0 > > softirqs last disabled at (10102337): [<ffffffff81066e86>] irq_exit+0x56/0xe0 > > Preemption disabled at:[<ffffffff817de50d>] printk_emit+0x31/0x33 > > > > CPU: 1 PID: 1 Comm: systemd Not tainted 3.18.0-rc2-next-20141029-dirty #222 > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140617_173321-var-lib-archbuild-testing-x86_64-tobias 04/01/2014 > > ffffffff81a82291 ffff88001e743978 ffffffff817df31d 0000000000000000 > > 0000000000000000 ffff88001e7439a8 ffffffff8108dfa2 ffff88001e7439a8 > > ffffffff81a82291 0000000000000068 0000000000000000 ffff88001e7439d8 > > Call Trace: > > [<ffffffff817df31d>] dump_stack+0x4f/0x7c > > [<ffffffff8108dfa2>] ___might_sleep+0x182/0x2b0 > > [<ffffffff8108e10a>] __might_sleep+0x3a/0xc0 > > [<ffffffff810ce358>] synchronize_irq+0x38/0xa0 > > [<ffffffff810ce690>] disable_irq+0x20/0x30 > > [<ffffffff815d7253>] e1000_netpoll+0x23/0x60 > > [<ffffffff81678d02>] netpoll_poll_dev+0x72/0x3a0 > > [<ffffffff816791e7>] netpoll_send_skb_on_dev+0x1b7/0x2e0 > > [<ffffffff816795f3>] netpoll_send_udp+0x2e3/0x490 > > Oh cute.. not entirely sure what to do there. This only works if you > _know_ desc->threads_active will never be !0. > > The best I can come up with is something like this, which avoids the > might_sleep() in the one special case. > > Thomas? Yuck. No. You are just papering over the problem. What happens if you add 'threadirqs' to the kernel command line? Or if the interrupt line is shared with a real threaded interrupt user? The proper solution is to have a poll_lock for e1000 which serializes the hardware interrupt against netpoll instead of using disable/enable_irq(). In fact that's less expensive than the disable/enable_irq() dance and the chance of contention is pretty low. If done right it will be a NOOP for the CONFIG_NET_POLL_CONTROLLER=n case. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 0a9104b4608b..b7cb736a8b32 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -100,8 +100,11 @@ void synchronize_irq(unsigned int irq) * running. Now verify that no threaded handlers are * active. */ - wait_event(desc->wait_for_threads, - !atomic_read(&desc->threads_active)); + if (atomic_read(&desc->threads_active)) { + might_sleep(); + __wait_event(desc->wait_for_threads, + !atomic_read(&desc->threads_active)); + } } } EXPORT_SYMBOL(synchronize_irq);