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Message-Id: <1396440673-18286-1-git-send-email-prarit@redhat.com>
Date: Wed, 2 Apr 2014 08:11:13 -0400
From: Prarit Bhargava <prarit@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Prarit Bhargava <prarit@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
Rui Wang <rui.y.wang@...el.com>,
Liu Ping Fan <kernelfans@...il.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>,
Lv Zheng <lv.zheng@...el.com>,
Seiji Aguchi <seiji.aguchi@....com>,
Yang Zhang <yang.z.zhang@...el.com>,
Andi Kleen <ak@...ux.intel.com>,
"Steven Rostedt (Red Hat)" <rostedt@...dmis.org>,
Li Fei <fei.li@...el.com>, gong.chen@...ux.intel.com
Subject: [PATCH] x86, fix x86 fixup_irqs() error handling [v3]
Resending ... didn't see this in tree yet and want to make sure it doesn't
get dropped.
Last submit here: http://marc.info/?l=linux-kernel&m=139453958911067&w=2
P.
---8<---
Several patches to fix cpu hotplug and the down'd cpu's irq relocations
have been submitted in the past month or so. The patches should resolve
the problems with cpu hotplug and irq relocation, however, there is
always a possibility that a bug still exists. The big problem with
debugging these irq reassignments is that the cpu down completes and then
we get random stack traces from drivers for which irqs have not been properly
assigned to a new cpu. The stack traces are a mix of storage, network,
and other kernel subsystem (I once saw the serial port stop working ...)
warnings and failures.
The problem with these failures is that they are difficult to diagnose.
There is no warning in the cpu hotplug down path to indicate that an IRQ
has failed to be assigned to a new cpu, and all we are left with is a
stack trace from a driver, or a non-functional device. If we had some
information on the console debugging these situations would be much
easier; after all we can map an IRQ to a device by simply using lspci or
/proc/interrupts.
The current code, fixup_irqs(), which migrates IRQs from the down'd cpu
and is called close to the end of the cpu down path, calls
chip->set_irq_affinity which eventually calls __assign_irq_vector().
Errors are not propogated back from this function call and this
results in silent irq relocation failures.
This patch fixes this issue by returning the error codes up the call
stack and prints out a warning if there is a relocation failure.
[v2]: modified WARN to pr_crit and changed message
[v3]: updated changelog to conform to standard changelog style
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Cc: Rui Wang <rui.y.wang@...el.com>
Cc: Liu Ping Fan <kernelfans@...il.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>
Cc: Lv Zheng <lv.zheng@...el.com>
Cc: Seiji Aguchi <seiji.aguchi@....com>
Cc: Yang Zhang <yang.z.zhang@...el.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: "Steven Rostedt (Red Hat)" <rostedt@...dmis.org>
Cc: Li Fei <fei.li@...el.com>
Cc: gong.chen@...ux.intel.com
Signed-off-by: Prarit Bhargava <prarit@...hat.com>
---
arch/x86/kernel/apic/io_apic.c | 28 ++++++++++++++++++----------
arch/x86/kernel/irq.c | 9 +++++++--
2 files changed, 25 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 6ad4658..b4b21db 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2312,7 +2312,7 @@ int __ioapic_set_affinity(struct irq_data *data, const struct cpumask *mask,
int err;
if (!config_enabled(CONFIG_SMP))
- return -1;
+ return -EPERM;
if (!cpumask_intersects(mask, cpu_online_mask))
return -EINVAL;
@@ -2343,7 +2343,7 @@ int native_ioapic_set_affinity(struct irq_data *data,
int ret;
if (!config_enabled(CONFIG_SMP))
- return -1;
+ return -EPERM;
raw_spin_lock_irqsave(&ioapic_lock, flags);
ret = __ioapic_set_affinity(data, mask, &dest);
@@ -3075,9 +3075,11 @@ msi_set_affinity(struct irq_data *data, const struct cpumask *mask, bool force)
struct irq_cfg *cfg = data->chip_data;
struct msi_msg msg;
unsigned int dest;
+ int ret;
- if (__ioapic_set_affinity(data, mask, &dest))
- return -1;
+ ret = __ioapic_set_affinity(data, mask, &dest);
+ if (ret)
+ return ret;
__get_cached_msi_msg(data->msi_desc, &msg);
@@ -3177,9 +3179,11 @@ dmar_msi_set_affinity(struct irq_data *data, const struct cpumask *mask,
struct irq_cfg *cfg = data->chip_data;
unsigned int dest, irq = data->irq;
struct msi_msg msg;
+ int ret;
- if (__ioapic_set_affinity(data, mask, &dest))
- return -1;
+ ret = __ioapic_set_affinity(data, mask, &dest);
+ if (ret)
+ return ret;
dmar_msi_read(irq, &msg);
@@ -3226,9 +3230,11 @@ static int hpet_msi_set_affinity(struct irq_data *data,
struct irq_cfg *cfg = data->chip_data;
struct msi_msg msg;
unsigned int dest;
+ int ret;
- if (__ioapic_set_affinity(data, mask, &dest))
- return -1;
+ ret = __ioapic_set_affinity(data, mask, &dest);
+ if (ret)
+ return ret;
hpet_msi_read(data->handler_data, &msg);
@@ -3295,9 +3301,11 @@ ht_set_affinity(struct irq_data *data, const struct cpumask *mask, bool force)
{
struct irq_cfg *cfg = data->chip_data;
unsigned int dest;
+ int ret;
- if (__ioapic_set_affinity(data, mask, &dest))
- return -1;
+ ret = __ioapic_set_affinity(data, mask, &dest);
+ if (ret)
+ return ret;
target_ht_irq(data->irq, dest, cfg->vector);
return IRQ_SET_MASK_OK_NOCOPY;
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index d99f31d..32a351d 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -351,6 +351,7 @@ void fixup_irqs(void)
struct irq_desc *desc;
struct irq_data *data;
struct irq_chip *chip;
+ int ret;
for_each_irq_desc(irq, desc) {
int break_affinity = 0;
@@ -389,8 +390,12 @@ void fixup_irqs(void)
if (!irqd_can_move_in_process_context(data) && chip->irq_mask)
chip->irq_mask(data);
- if (chip->irq_set_affinity)
- chip->irq_set_affinity(data, affinity, true);
+ if (chip->irq_set_affinity) {
+ ret = chip->irq_set_affinity(data, affinity, true);
+ if (ret == -ENOSPC)
+ pr_crit("IRQ %d set affinity failed because there are no available vectors. The device assigned to this IRQ is unstable.\n",
+ irq);
+ }
else if (!(warned++))
set_affinity = 0;
--
1.7.9.3
--
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