* [PATCH] irqchip/gicv3: silence noisy DEBUG_PER_CPU_MAPS warning
@ 2016-09-19 17:29 James Morse
2016-09-19 17:38 ` Marc Zyngier
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: James Morse @ 2016-09-19 17:29 UTC (permalink / raw)
To: linux-kernel
Cc: linux-arm-kernel, Thomas Gleixner, Jason Cooper, Marc Zyngier,
James Morse
gic_raise_softirq() walks the list of cpus using for_each_cpu(), it calls
gic_compute_target_list() which advances the iterator by the number of
CPUs in the cluster.
If gic_compute_target_list() reaches the last CPU it leaves the iterator
pointing at the last CPU. This means the next time round the for_each_cpu()
loop cpumask_next() will be called with an invalid CPU.
This triggers a warning when built with CONFIG_DEBUG_PER_CPU_MAPS:
[ 3.077738] GICv3: CPU1: found redistributor 1 region 0:0x000000002f120000
[ 3.077943] CPU1: Booted secondary processor [410fd0f0]
[ 3.078542] ------------[ cut here ]------------
[ 3.078746] WARNING: CPU: 1 PID: 0 at ../include/linux/cpumask.h:121 gic_raise_softirq+0x12c/0x170
[ 3.078812] Modules linked in:
[ 3.078869]
[ 3.078930] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0-rc5+ #5188
[ 3.078994] Hardware name: Foundation-v8A (DT)
[ 3.079059] task: ffff80087a1a0080 task.stack: ffff80087a19c000
[ 3.079145] PC is at gic_raise_softirq+0x12c/0x170
[ 3.079226] LR is at gic_raise_softirq+0xa4/0x170
[ 3.079296] pc : [<ffff0000083ead24>] lr : [<ffff0000083eac9c>] pstate: 200001c9
[ 3.081139] Call trace:
[ 3.081202] Exception stack(0xffff80087a19fbe0 to 0xffff80087a19fd10)
[ 3.082269] [<ffff0000083ead24>] gic_raise_softirq+0x12c/0x170
[ 3.082354] [<ffff00000808e614>] smp_send_reschedule+0x34/0x40
[ 3.082433] [<ffff0000080e80a0>] resched_curr+0x50/0x88
[ 3.082512] [<ffff0000080e89d0>] check_preempt_curr+0x60/0xd0
[ 3.082593] [<ffff0000080e8a60>] ttwu_do_wakeup+0x20/0xe8
[ 3.082672] [<ffff0000080e8bb8>] ttwu_do_activate+0x90/0xc0
[ 3.082753] [<ffff0000080ea9a4>] try_to_wake_up+0x224/0x370
[ 3.082836] [<ffff0000080eabc8>] default_wake_function+0x10/0x18
[ 3.082920] [<ffff000008103134>] __wake_up_common+0x5c/0xa0
[ 3.083003] [<ffff0000081031f4>] __wake_up_locked+0x14/0x20
[ 3.083086] [<ffff000008103f80>] complete+0x40/0x60
[ 3.083168] [<ffff00000808df7c>] secondary_start_kernel+0x15c/0x1d0
[ 3.083240] [<00000000808911a4>] 0x808911a4
[ 3.113401] Detected PIPT I-cache on CPU2
Avoid updating the iterator if the next call to cpumask_next() would
cause the for_each_cpu() loop to exit.
There is no change to gic_raise_softirq()'s behaviour, (cpumask_next()s
eventual call to _find_next_bit() will return early as start >= nbits),
this patch just silences the warning.
Signed-off-by: James Morse <james.morse@arm.com>
---
drivers/irqchip/irq-gic-v3.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index ede5672ab34d..9e37c447cc2c 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -548,6 +548,7 @@ static int gic_starting_cpu(unsigned int cpu)
static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
unsigned long cluster_id)
{
+ int next_cpu;
int cpu = *base_cpu;
unsigned long mpidr = cpu_logical_map(cpu);
u16 tlist = 0;
@@ -562,9 +563,10 @@ static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
tlist |= 1 << (mpidr & 0xf);
- cpu = cpumask_next(cpu, mask);
- if (cpu >= nr_cpu_ids)
+ next_cpu = cpumask_next(cpu, mask);
+ if (next_cpu >= nr_cpu_ids)
goto out;
+ cpu = next_cpu;
mpidr = cpu_logical_map(cpu);
--
2.8.0.rc3
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] irqchip/gicv3: silence noisy DEBUG_PER_CPU_MAPS warning
2016-09-19 17:29 [PATCH] irqchip/gicv3: silence noisy DEBUG_PER_CPU_MAPS warning James Morse
@ 2016-09-19 17:38 ` Marc Zyngier
2016-09-19 19:13 ` [tip:irq/urgent] irqchip/gicv3: Silence " tip-bot for James Morse
2016-09-19 23:48 ` tip-bot for James Morse
2 siblings, 0 replies; 4+ messages in thread
From: Marc Zyngier @ 2016-09-19 17:38 UTC (permalink / raw)
To: James Morse, linux-kernel; +Cc: linux-arm-kernel, Thomas Gleixner, Jason Cooper
Hi James,
On 19/09/16 18:29, James Morse wrote:
> gic_raise_softirq() walks the list of cpus using for_each_cpu(), it calls
> gic_compute_target_list() which advances the iterator by the number of
> CPUs in the cluster.
>
> If gic_compute_target_list() reaches the last CPU it leaves the iterator
> pointing at the last CPU. This means the next time round the for_each_cpu()
> loop cpumask_next() will be called with an invalid CPU.
>
> This triggers a warning when built with CONFIG_DEBUG_PER_CPU_MAPS:
> [ 3.077738] GICv3: CPU1: found redistributor 1 region 0:0x000000002f120000
> [ 3.077943] CPU1: Booted secondary processor [410fd0f0]
> [ 3.078542] ------------[ cut here ]------------
> [ 3.078746] WARNING: CPU: 1 PID: 0 at ../include/linux/cpumask.h:121 gic_raise_softirq+0x12c/0x170
> [ 3.078812] Modules linked in:
> [ 3.078869]
> [ 3.078930] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0-rc5+ #5188
> [ 3.078994] Hardware name: Foundation-v8A (DT)
> [ 3.079059] task: ffff80087a1a0080 task.stack: ffff80087a19c000
> [ 3.079145] PC is at gic_raise_softirq+0x12c/0x170
> [ 3.079226] LR is at gic_raise_softirq+0xa4/0x170
> [ 3.079296] pc : [<ffff0000083ead24>] lr : [<ffff0000083eac9c>] pstate: 200001c9
> [ 3.081139] Call trace:
> [ 3.081202] Exception stack(0xffff80087a19fbe0 to 0xffff80087a19fd10)
>
> [ 3.082269] [<ffff0000083ead24>] gic_raise_softirq+0x12c/0x170
> [ 3.082354] [<ffff00000808e614>] smp_send_reschedule+0x34/0x40
> [ 3.082433] [<ffff0000080e80a0>] resched_curr+0x50/0x88
> [ 3.082512] [<ffff0000080e89d0>] check_preempt_curr+0x60/0xd0
> [ 3.082593] [<ffff0000080e8a60>] ttwu_do_wakeup+0x20/0xe8
> [ 3.082672] [<ffff0000080e8bb8>] ttwu_do_activate+0x90/0xc0
> [ 3.082753] [<ffff0000080ea9a4>] try_to_wake_up+0x224/0x370
> [ 3.082836] [<ffff0000080eabc8>] default_wake_function+0x10/0x18
> [ 3.082920] [<ffff000008103134>] __wake_up_common+0x5c/0xa0
> [ 3.083003] [<ffff0000081031f4>] __wake_up_locked+0x14/0x20
> [ 3.083086] [<ffff000008103f80>] complete+0x40/0x60
> [ 3.083168] [<ffff00000808df7c>] secondary_start_kernel+0x15c/0x1d0
> [ 3.083240] [<00000000808911a4>] 0x808911a4
> [ 3.113401] Detected PIPT I-cache on CPU2
>
> Avoid updating the iterator if the next call to cpumask_next() would
> cause the for_each_cpu() loop to exit.
>
> There is no change to gic_raise_softirq()'s behaviour, (cpumask_next()s
> eventual call to _find_next_bit() will return early as start >= nbits),
> this patch just silences the warning.
>
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
> drivers/irqchip/irq-gic-v3.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index ede5672ab34d..9e37c447cc2c 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -548,6 +548,7 @@ static int gic_starting_cpu(unsigned int cpu)
> static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
> unsigned long cluster_id)
> {
> + int next_cpu;
> int cpu = *base_cpu;
> unsigned long mpidr = cpu_logical_map(cpu);
> u16 tlist = 0;
> @@ -562,9 +563,10 @@ static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
>
> tlist |= 1 << (mpidr & 0xf);
>
> - cpu = cpumask_next(cpu, mask);
> - if (cpu >= nr_cpu_ids)
> + next_cpu = cpumask_next(cpu, mask);
> + if (next_cpu >= nr_cpu_ids)
> goto out;
> + cpu = next_cpu;
>
> mpidr = cpu_logical_map(cpu);
>
>
It took me a while to convince myself that the original code was
correct, and it obviously wasn't... Oh well, paper bag time.
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Thomas, any chance you could pick that one for -rc8?
Thanks,
M.
--
Jazz is not dead. It just smells funny...
^ permalink raw reply [flat|nested] 4+ messages in thread
* [tip:irq/urgent] irqchip/gicv3: Silence noisy DEBUG_PER_CPU_MAPS warning
2016-09-19 17:29 [PATCH] irqchip/gicv3: silence noisy DEBUG_PER_CPU_MAPS warning James Morse
2016-09-19 17:38 ` Marc Zyngier
@ 2016-09-19 19:13 ` tip-bot for James Morse
2016-09-19 23:48 ` tip-bot for James Morse
2 siblings, 0 replies; 4+ messages in thread
From: tip-bot for James Morse @ 2016-09-19 19:13 UTC (permalink / raw)
To: linux-tip-commits
Cc: jason, tglx, marc.zyngier, mingo, james.morse, linux-kernel, hpa
Commit-ID: 7e947926fc3bfa095644c2933ec209128cbfd61e
Gitweb: http://git.kernel.org/tip/7e947926fc3bfa095644c2933ec209128cbfd61e
Author: James Morse <james.morse@arm.com>
AuthorDate: Mon, 19 Sep 2016 18:29:15 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 19 Sep 2016 21:07:12 +0200
irqchip/gicv3: Silence noisy DEBUG_PER_CPU_MAPS warning
gic_raise_softirq() walks the list of cpus using for_each_cpu(), it calls
gic_compute_target_list() which advances the iterator by the number of
CPUs in the cluster.
If gic_compute_target_list() reaches the last CPU it leaves the iterator
pointing at the last CPU. This means the next time round the for_each_cpu()
loop cpumask_next() will be called with an invalid CPU.
This triggers a warning when built with CONFIG_DEBUG_PER_CPU_MAPS:
[ 3.077738] GICv3: CPU1: found redistributor 1 region 0:0x000000002f120000
[ 3.077943] CPU1: Booted secondary processor [410fd0f0]
[ 3.078542] ------------[ cut here ]------------
[ 3.078746] WARNING: CPU: 1 PID: 0 at ../include/linux/cpumask.h:121 gic_raise_softirq+0x12c/0x170
[ 3.078812] Modules linked in:
[ 3.078869]
[ 3.078930] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0-rc5+ #5188
[ 3.078994] Hardware name: Foundation-v8A (DT)
[ 3.079059] task: ffff80087a1a0080 task.stack: ffff80087a19c000
[ 3.079145] PC is at gic_raise_softirq+0x12c/0x170
[ 3.079226] LR is at gic_raise_softirq+0xa4/0x170
[ 3.079296] pc : [<ffff0000083ead24>] lr : [<ffff0000083eac9c>] pstate: 200001c9
[ 3.081139] Call trace:
[ 3.081202] Exception stack(0xffff80087a19fbe0 to 0xffff80087a19fd10)
[ 3.082269] [<ffff0000083ead24>] gic_raise_softirq+0x12c/0x170
[ 3.082354] [<ffff00000808e614>] smp_send_reschedule+0x34/0x40
[ 3.082433] [<ffff0000080e80a0>] resched_curr+0x50/0x88
[ 3.082512] [<ffff0000080e89d0>] check_preempt_curr+0x60/0xd0
[ 3.082593] [<ffff0000080e8a60>] ttwu_do_wakeup+0x20/0xe8
[ 3.082672] [<ffff0000080e8bb8>] ttwu_do_activate+0x90/0xc0
[ 3.082753] [<ffff0000080ea9a4>] try_to_wake_up+0x224/0x370
[ 3.082836] [<ffff0000080eabc8>] default_wake_function+0x10/0x18
[ 3.082920] [<ffff000008103134>] __wake_up_common+0x5c/0xa0
[ 3.083003] [<ffff0000081031f4>] __wake_up_locked+0x14/0x20
[ 3.083086] [<ffff000008103f80>] complete+0x40/0x60
[ 3.083168] [<ffff00000808df7c>] secondary_start_kernel+0x15c/0x1d0
[ 3.083240] [<00000000808911a4>] 0x808911a4
[ 3.113401] Detected PIPT I-cache on CPU2
Avoid updating the iterator if the next call to cpumask_next() would
cause the for_each_cpu() loop to exit.
There is no change to gic_raise_softirq()'s behaviour, (cpumask_next()s
eventual call to _find_next_bit() will return early as start >= nbits),
this patch just silences the warning.
Fixes: 021f653791ad ("irqchip: gic-v3: Initial support for GICv3")
Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1474306155-3303-1-git-send-email-james.morse@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
drivers/irqchip/irq-gic-v3.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index ede5672..f39ab57 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -548,8 +548,8 @@ static int gic_starting_cpu(unsigned int cpu)
static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
unsigned long cluster_id)
{
- int cpu = *base_cpu;
unsigned long mpidr = cpu_logical_map(cpu);
+ int next_cpu, cpu = *base_cpu;
u16 tlist = 0;
while (cpu < nr_cpu_ids) {
@@ -562,9 +562,10 @@ static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
tlist |= 1 << (mpidr & 0xf);
- cpu = cpumask_next(cpu, mask);
- if (cpu >= nr_cpu_ids)
+ next_cpu = cpumask_next(cpu, mask);
+ if (next_cpu >= nr_cpu_ids)
goto out;
+ cpu = next_cpu;
mpidr = cpu_logical_map(cpu);
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [tip:irq/urgent] irqchip/gicv3: Silence noisy DEBUG_PER_CPU_MAPS warning
2016-09-19 17:29 [PATCH] irqchip/gicv3: silence noisy DEBUG_PER_CPU_MAPS warning James Morse
2016-09-19 17:38 ` Marc Zyngier
2016-09-19 19:13 ` [tip:irq/urgent] irqchip/gicv3: Silence " tip-bot for James Morse
@ 2016-09-19 23:48 ` tip-bot for James Morse
2 siblings, 0 replies; 4+ messages in thread
From: tip-bot for James Morse @ 2016-09-19 23:48 UTC (permalink / raw)
To: linux-tip-commits
Cc: tglx, james.morse, hpa, jason, linux-kernel, marc.zyngier, mingo
Commit-ID: 727653d6ce7103b245eb8041f55dd5885f4c3289
Gitweb: http://git.kernel.org/tip/727653d6ce7103b245eb8041f55dd5885f4c3289
Author: James Morse <james.morse@arm.com>
AuthorDate: Mon, 19 Sep 2016 18:29:15 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 20 Sep 2016 01:43:23 +0200
irqchip/gicv3: Silence noisy DEBUG_PER_CPU_MAPS warning
gic_raise_softirq() walks the list of cpus using for_each_cpu(), it calls
gic_compute_target_list() which advances the iterator by the number of
CPUs in the cluster.
If gic_compute_target_list() reaches the last CPU it leaves the iterator
pointing at the last CPU. This means the next time round the for_each_cpu()
loop cpumask_next() will be called with an invalid CPU.
This triggers a warning when built with CONFIG_DEBUG_PER_CPU_MAPS:
[ 3.077738] GICv3: CPU1: found redistributor 1 region 0:0x000000002f120000
[ 3.077943] CPU1: Booted secondary processor [410fd0f0]
[ 3.078542] ------------[ cut here ]------------
[ 3.078746] WARNING: CPU: 1 PID: 0 at ../include/linux/cpumask.h:121 gic_raise_softirq+0x12c/0x170
[ 3.078812] Modules linked in:
[ 3.078869]
[ 3.078930] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.8.0-rc5+ #5188
[ 3.078994] Hardware name: Foundation-v8A (DT)
[ 3.079059] task: ffff80087a1a0080 task.stack: ffff80087a19c000
[ 3.079145] PC is at gic_raise_softirq+0x12c/0x170
[ 3.079226] LR is at gic_raise_softirq+0xa4/0x170
[ 3.079296] pc : [<ffff0000083ead24>] lr : [<ffff0000083eac9c>] pstate: 200001c9
[ 3.081139] Call trace:
[ 3.081202] Exception stack(0xffff80087a19fbe0 to 0xffff80087a19fd10)
[ 3.082269] [<ffff0000083ead24>] gic_raise_softirq+0x12c/0x170
[ 3.082354] [<ffff00000808e614>] smp_send_reschedule+0x34/0x40
[ 3.082433] [<ffff0000080e80a0>] resched_curr+0x50/0x88
[ 3.082512] [<ffff0000080e89d0>] check_preempt_curr+0x60/0xd0
[ 3.082593] [<ffff0000080e8a60>] ttwu_do_wakeup+0x20/0xe8
[ 3.082672] [<ffff0000080e8bb8>] ttwu_do_activate+0x90/0xc0
[ 3.082753] [<ffff0000080ea9a4>] try_to_wake_up+0x224/0x370
[ 3.082836] [<ffff0000080eabc8>] default_wake_function+0x10/0x18
[ 3.082920] [<ffff000008103134>] __wake_up_common+0x5c/0xa0
[ 3.083003] [<ffff0000081031f4>] __wake_up_locked+0x14/0x20
[ 3.083086] [<ffff000008103f80>] complete+0x40/0x60
[ 3.083168] [<ffff00000808df7c>] secondary_start_kernel+0x15c/0x1d0
[ 3.083240] [<00000000808911a4>] 0x808911a4
[ 3.113401] Detected PIPT I-cache on CPU2
Avoid updating the iterator if the next call to cpumask_next() would
cause the for_each_cpu() loop to exit.
There is no change to gic_raise_softirq()'s behaviour, (cpumask_next()s
eventual call to _find_next_bit() will return early as start >= nbits),
this patch just silences the warning.
Fixes: 021f653791ad ("irqchip: gic-v3: Initial support for GICv3")
Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1474306155-3303-1-git-send-email-james.morse@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
drivers/irqchip/irq-gic-v3.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index ede5672..da6c0ba 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -548,7 +548,7 @@ static int gic_starting_cpu(unsigned int cpu)
static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
unsigned long cluster_id)
{
- int cpu = *base_cpu;
+ int next_cpu, cpu = *base_cpu;
unsigned long mpidr = cpu_logical_map(cpu);
u16 tlist = 0;
@@ -562,9 +562,10 @@ static u16 gic_compute_target_list(int *base_cpu, const struct cpumask *mask,
tlist |= 1 << (mpidr & 0xf);
- cpu = cpumask_next(cpu, mask);
- if (cpu >= nr_cpu_ids)
+ next_cpu = cpumask_next(cpu, mask);
+ if (next_cpu >= nr_cpu_ids)
goto out;
+ cpu = next_cpu;
mpidr = cpu_logical_map(cpu);
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2016-09-19 23:48 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-09-19 17:29 [PATCH] irqchip/gicv3: silence noisy DEBUG_PER_CPU_MAPS warning James Morse
2016-09-19 17:38 ` Marc Zyngier
2016-09-19 19:13 ` [tip:irq/urgent] irqchip/gicv3: Silence " tip-bot for James Morse
2016-09-19 23:48 ` tip-bot for James Morse
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