From: Thomas Gleixner <tglx@linutronix.de>
To: Evan Green <evgreen@chromium.org>
Cc: Rajat Jain <rajatja@google.com>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-pci <linux-pci@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
x86@kernel.org, Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH v2] PCI/MSI: Avoid torn updates to MSI pairs
Date: Tue, 28 Jan 2020 23:48:32 +0100 [thread overview]
Message-ID: <87pnf342pr.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <CAE=gft7Gu0ah4qcbsEB1X+kUMagCzPR+cdCfn2caofcGV+tBjA@mail.gmail.com>
Evan,
Evan Green <evgreen@chromium.org> writes:
> On Tue, Jan 28, 2020 at 6:38 AM Thomas Gleixner <tglx@linutronix.de> wrote:
>> The patch is only lightly tested, but so far it survived.
>>
>
> Hi Thomas,
> Thanks for the patch, I gave it a try. I get the following splat, then a hang:
>
> [ 62.238406] CPU0
> [ 62.241135] ----
> [ 62.243863] lock(vector_lock);
> [ 62.247467] lock(vector_lock);
> [ 62.251071]
> [ 62.251071] *** DEADLOCK ***
> [ 62.251071]
> [ 62.257687] May be due to missing lock nesting notation
> [ 62.257687]
> [ 62.265274] 2 locks held by migration/1/17:
> [ 62.269946] #0: 00000000cfa9d8c3 (&irq_desc_lock_class){-.-.}, at:
> irq_migrate_all_off_this_cpu+0x44/0x28f
> [ 62.280846] #1: 000000006885da2d (vector_lock){-.-.}, at:
> msi_set_affinity+0x13c/0x27b
> [ 62.289801]
> [ 62.289801] stack backtrace:
> [ 62.294669] CPU: 1 PID: 17 Comm: migration/1 Not tainted 4.19.96 #2
> [ 62.310713] Call Trace:
> [ 62.313446] dump_stack+0xac/0x11e
> [ 62.317255] __lock_acquire+0x64f/0x19bc
> [ 62.321646] ? find_held_lock+0x3d/0xb8
> [ 62.325936] ? pci_conf1_write+0x4f/0xdf
> [ 62.330320] lock_acquire+0x1b2/0x1fa
> [ 62.334413] ? apic_retrigger_irq+0x31/0x63
> [ 62.339097] _raw_spin_lock_irqsave+0x51/0x7d
> [ 62.343972] ? apic_retrigger_irq+0x31/0x63
> [ 62.348646] apic_retrigger_irq+0x31/0x63
> [ 62.353124] msi_set_affinity+0x25a/0x27b
Bah. I'm sure I looked at that call chain, noticed the double vector
lock and then forgot. Delta patch below.
Thanks,
tglx
8<--------------
--- a/arch/x86/kernel/apic/msi.c
+++ b/arch/x86/kernel/apic/msi.c
@@ -64,6 +64,7 @@ msi_set_affinity(struct irq_data *irqd,
struct irq_cfg old_cfg, *cfg = irqd_cfg(irqd);
struct irq_data *parent = irqd->parent_data;
unsigned int cpu;
+ bool pending;
int ret;
/* Save the current configuration */
@@ -147,9 +148,13 @@ msi_set_affinity(struct irq_data *irqd,
* vector/CPU. Check whether the transition raced with a device
* interrupt and is pending in the local APICs IRR.
*/
- if (lapic_vector_set_in_irr(cfg->vector))
- irq_data_get_irq_chip(irqd)->irq_retrigger(irqd);
+ pending = lapic_vector_set_in_irr(cfg->vector);
+
unlock_vector_lock();
+
+ if (pending)
+ irq_data_get_irq_chip(irqd)->irq_retrigger(irqd);
+
return ret;
}
next prev parent reply other threads:[~2020-01-28 22:48 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-18 0:25 [PATCH v2] PCI/MSI: Avoid torn updates to MSI pairs Evan Green
2020-01-22 11:25 ` Rajat Jain
2020-01-22 18:00 ` Evan Green
2020-01-23 8:49 ` Thomas Gleixner
2020-01-23 18:16 ` Thomas Gleixner
[not found] ` <CAE=gft6YiM5S1A7iJYJTd5zmaAa8=nhLE3B94JtWa+XW-qVSqQ@mail.gmail.com>
2020-01-23 22:59 ` Evan Green
2020-01-24 0:29 ` Evan Green
2020-01-24 14:34 ` Thomas Gleixner
2020-01-24 21:53 ` Evan Green
2020-01-24 22:50 ` Thomas Gleixner
2020-01-28 14:38 ` Thomas Gleixner
2020-01-28 22:22 ` Evan Green
2020-01-28 22:48 ` Thomas Gleixner [this message]
2020-01-29 18:00 ` Evan Green
2020-01-29 21:00 ` Thomas Gleixner
2020-01-29 22:53 ` Evan Green
2020-01-29 23:16 ` Thomas Gleixner
2020-01-29 23:48 ` Evan Green
2020-01-31 11:27 ` [PATCH] x86/apic/msi: Plug non-maskable MSI affinity race Thomas Gleixner
2020-01-31 14:26 ` [PATCH V2] " Thomas Gleixner
2020-01-31 20:32 ` Evan Green
2020-01-31 21:45 ` Thomas Gleixner
2020-02-01 8:36 ` [tip: x86/urgent] " tip-bot2 for Thomas Gleixner
2020-01-24 0:50 ` [PATCH v2] PCI/MSI: Avoid torn updates to MSI pairs Thomas Gleixner
2020-01-25 18:32 ` Jacob Pan
2020-01-26 8:09 ` Thomas Gleixner
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