* [PATCH v2 1/2] rcu: Create a function for rcu_nocb_mask boot time setup
@ 2014-07-25 0:37 Pranith Kumar
2014-07-25 0:37 ` [PATCH v2 2/2] rcu: Check the return value of rcu_nocb_mask cpumask allocation Pranith Kumar
2014-07-25 15:27 ` [PATCH v2 1/2] rcu: Create a function for rcu_nocb_mask boot time setup Paul E. McKenney
0 siblings, 2 replies; 6+ messages in thread
From: Pranith Kumar @ 2014-07-25 0:37 UTC (permalink / raw)
To: Paul E. McKenney, Josh Triplett, Steven Rostedt,
Mathieu Desnoyers, Lai Jiangshan, open list:READ-COPY UPDATE...
This commit creates a function rcu_bootup_announce_oddness_nocb(), which handles
allocation of rcu_nocb_mask and setting it according to the kernel configuration
parameters.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
---
v2: don't break the print string (comment from paulmck)
kernel/rcu/tree_plugin.h | 61 +++++++++++++++++++++++++++---------------------
1 file changed, 35 insertions(+), 26 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index c31eb28..520538a 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -47,6 +47,39 @@ static char __initdata nocb_buf[NR_CPUS * 5];
#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
/*
+ * This is a helper for rcu_bootup_announce_oddness(), which takes care of
+ * setting up rcu_nocb_mask for nocb specific kernel configuration parameters
+ */
+static void __init rcu_bootup_announce_oddness_nocb(void)
+{
+#ifndef CONFIG_RCU_NOCB_CPU_NONE
+ if (!have_rcu_nocb_mask) {
+ zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL);
+ have_rcu_nocb_mask = true;
+ }
+#ifdef CONFIG_RCU_NOCB_CPU_ZERO
+ pr_info("\tOffload RCU callbacks from CPU 0\n");
+ cpumask_set_cpu(0, rcu_nocb_mask);
+#endif /* #ifdef CONFIG_RCU_NOCB_CPU_ZERO */
+#ifdef CONFIG_RCU_NOCB_CPU_ALL
+ pr_info("\tOffload RCU callbacks from all CPUs\n");
+ cpumask_copy(rcu_nocb_mask, cpu_possible_mask);
+#endif /* #ifdef CONFIG_RCU_NOCB_CPU_ALL */
+#endif /* #ifndef CONFIG_RCU_NOCB_CPU_NONE */
+ if (have_rcu_nocb_mask) {
+ if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
+ pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
+ cpumask_and(rcu_nocb_mask, cpu_possible_mask,
+ rcu_nocb_mask);
+ }
+ cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
+ pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
+ if (rcu_nocb_poll)
+ pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
+ }
+}
+
+/*
* Check the RCU kernel configuration parameters and print informative
* messages about anything out of the ordinary. If you like #ifdef, you
* will love this function.
@@ -86,32 +119,8 @@ static void __init rcu_bootup_announce_oddness(void)
if (nr_cpu_ids != NR_CPUS)
pr_info("\tRCU restricting CPUs from NR_CPUS=%d to nr_cpu_ids=%d.\n", NR_CPUS, nr_cpu_ids);
#ifdef CONFIG_RCU_NOCB_CPU
-#ifndef CONFIG_RCU_NOCB_CPU_NONE
- if (!have_rcu_nocb_mask) {
- zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL);
- have_rcu_nocb_mask = true;
- }
-#ifdef CONFIG_RCU_NOCB_CPU_ZERO
- pr_info("\tOffload RCU callbacks from CPU 0\n");
- cpumask_set_cpu(0, rcu_nocb_mask);
-#endif /* #ifdef CONFIG_RCU_NOCB_CPU_ZERO */
-#ifdef CONFIG_RCU_NOCB_CPU_ALL
- pr_info("\tOffload RCU callbacks from all CPUs\n");
- cpumask_copy(rcu_nocb_mask, cpu_possible_mask);
-#endif /* #ifdef CONFIG_RCU_NOCB_CPU_ALL */
-#endif /* #ifndef CONFIG_RCU_NOCB_CPU_NONE */
- if (have_rcu_nocb_mask) {
- if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
- pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
- cpumask_and(rcu_nocb_mask, cpu_possible_mask,
- rcu_nocb_mask);
- }
- cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
- pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
- if (rcu_nocb_poll)
- pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
- }
-#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
+ rcu_bootup_announce_oddness_nocb();
+#endif
}
#ifdef CONFIG_TREE_PREEMPT_RCU
--
2.0.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v2 2/2] rcu: Check the return value of rcu_nocb_mask cpumask allocation
2014-07-25 0:37 [PATCH v2 1/2] rcu: Create a function for rcu_nocb_mask boot time setup Pranith Kumar
@ 2014-07-25 0:37 ` Pranith Kumar
2014-07-25 15:25 ` Paul E. McKenney
2014-07-25 15:27 ` [PATCH v2 1/2] rcu: Create a function for rcu_nocb_mask boot time setup Paul E. McKenney
1 sibling, 1 reply; 6+ messages in thread
From: Pranith Kumar @ 2014-07-25 0:37 UTC (permalink / raw)
To: Paul E. McKenney, Josh Triplett, Steven Rostedt,
Mathieu Desnoyers, Lai Jiangshan, open list:READ-COPY UPDATE...
This commit checks the return value of the zalloc_cpumask_var() used for
allocating cpumask for rcu_nocb_mask.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
---
v2: no change from v1
kernel/rcu/tree_plugin.h | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 520538a..9c9a01c 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -54,7 +54,10 @@ static void __init rcu_bootup_announce_oddness_nocb(void)
{
#ifndef CONFIG_RCU_NOCB_CPU_NONE
if (!have_rcu_nocb_mask) {
- zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL);
+ if (!zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL)) {
+ pr_info("rcu_nocb_mask allocation failed\n");
+ return;
+ }
have_rcu_nocb_mask = true;
}
#ifdef CONFIG_RCU_NOCB_CPU_ZERO
@@ -66,17 +69,15 @@ static void __init rcu_bootup_announce_oddness_nocb(void)
cpumask_copy(rcu_nocb_mask, cpu_possible_mask);
#endif /* #ifdef CONFIG_RCU_NOCB_CPU_ALL */
#endif /* #ifndef CONFIG_RCU_NOCB_CPU_NONE */
- if (have_rcu_nocb_mask) {
- if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
- pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
- cpumask_and(rcu_nocb_mask, cpu_possible_mask,
- rcu_nocb_mask);
- }
- cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
- pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
- if (rcu_nocb_poll)
- pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
+ if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
+ pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
+ cpumask_and(rcu_nocb_mask, cpu_possible_mask,
+ rcu_nocb_mask);
}
+ cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
+ pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
+ if (rcu_nocb_poll)
+ pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
}
/*
--
2.0.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2 2/2] rcu: Check the return value of rcu_nocb_mask cpumask allocation
2014-07-25 0:37 ` [PATCH v2 2/2] rcu: Check the return value of rcu_nocb_mask cpumask allocation Pranith Kumar
@ 2014-07-25 15:25 ` Paul E. McKenney
2014-07-25 18:06 ` Paul E. McKenney
0 siblings, 1 reply; 6+ messages in thread
From: Paul E. McKenney @ 2014-07-25 15:25 UTC (permalink / raw)
To: Pranith Kumar
Cc: Josh Triplett, Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan,
open list:READ-COPY UPDATE...
On Thu, Jul 24, 2014 at 08:37:32PM -0400, Pranith Kumar wrote:
> This commit checks the return value of the zalloc_cpumask_var() used for
> allocating cpumask for rcu_nocb_mask.
>
> Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Hmmm... I saw the check in the previous patch, but didn't see removal
of the later have_rcu_nocb_mask check. Please see below.
Thanx, Paul
> ---
> v2: no change from v1
>
> kernel/rcu/tree_plugin.h | 23 ++++++++++++-----------
> 1 file changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> index 520538a..9c9a01c 100644
> --- a/kernel/rcu/tree_plugin.h
> +++ b/kernel/rcu/tree_plugin.h
> @@ -54,7 +54,10 @@ static void __init rcu_bootup_announce_oddness_nocb(void)
> {
> #ifndef CONFIG_RCU_NOCB_CPU_NONE
> if (!have_rcu_nocb_mask) {
> - zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL);
> + if (!zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL)) {
> + pr_info("rcu_nocb_mask allocation failed\n");
> + return;
> + }
> have_rcu_nocb_mask = true;
> }
> #ifdef CONFIG_RCU_NOCB_CPU_ZERO
> @@ -66,17 +69,15 @@ static void __init rcu_bootup_announce_oddness_nocb(void)
> cpumask_copy(rcu_nocb_mask, cpu_possible_mask);
> #endif /* #ifdef CONFIG_RCU_NOCB_CPU_ALL */
> #endif /* #ifndef CONFIG_RCU_NOCB_CPU_NONE */
> - if (have_rcu_nocb_mask) {
> - if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
> - pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
> - cpumask_and(rcu_nocb_mask, cpu_possible_mask,
> - rcu_nocb_mask);
> - }
> - cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
> - pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
> - if (rcu_nocb_poll)
> - pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
> + if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
What happens if CONFIG_RCU_NOCB_CPU_NONE=y and the rcu_nocbs= boot
parameter is not specified and we get here?
In order to get visible failures when testing, build with
CONFIG_CPUMASK_OFFSTACK=y.
> + pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
> + cpumask_and(rcu_nocb_mask, cpu_possible_mask,
> + rcu_nocb_mask);
> }
> + cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
> + pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
> + if (rcu_nocb_poll)
> + pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
> }
>
> /*
> --
> 2.0.1
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/2] rcu: Create a function for rcu_nocb_mask boot time setup
2014-07-25 0:37 [PATCH v2 1/2] rcu: Create a function for rcu_nocb_mask boot time setup Pranith Kumar
2014-07-25 0:37 ` [PATCH v2 2/2] rcu: Check the return value of rcu_nocb_mask cpumask allocation Pranith Kumar
@ 2014-07-25 15:27 ` Paul E. McKenney
1 sibling, 0 replies; 6+ messages in thread
From: Paul E. McKenney @ 2014-07-25 15:27 UTC (permalink / raw)
To: Pranith Kumar
Cc: Josh Triplett, Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan,
open list:READ-COPY UPDATE...
On Thu, Jul 24, 2014 at 08:37:31PM -0400, Pranith Kumar wrote:
> This commit creates a function rcu_bootup_announce_oddness_nocb(), which handles
> allocation of rcu_nocb_mask and setting it according to the kernel configuration
> parameters.
>
> Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Much better!
One more change called out below.
Thanx, Paul
> ---
> v2: don't break the print string (comment from paulmck)
>
> kernel/rcu/tree_plugin.h | 61 +++++++++++++++++++++++++++---------------------
> 1 file changed, 35 insertions(+), 26 deletions(-)
>
> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> index c31eb28..520538a 100644
> --- a/kernel/rcu/tree_plugin.h
> +++ b/kernel/rcu/tree_plugin.h
> @@ -47,6 +47,39 @@ static char __initdata nocb_buf[NR_CPUS * 5];
> #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
>
> /*
> + * This is a helper for rcu_bootup_announce_oddness(), which takes care of
> + * setting up rcu_nocb_mask for nocb specific kernel configuration parameters
> + */
> +static void __init rcu_bootup_announce_oddness_nocb(void)
> +{
> +#ifndef CONFIG_RCU_NOCB_CPU_NONE
> + if (!have_rcu_nocb_mask) {
> + zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL);
> + have_rcu_nocb_mask = true;
> + }
> +#ifdef CONFIG_RCU_NOCB_CPU_ZERO
> + pr_info("\tOffload RCU callbacks from CPU 0\n");
> + cpumask_set_cpu(0, rcu_nocb_mask);
> +#endif /* #ifdef CONFIG_RCU_NOCB_CPU_ZERO */
> +#ifdef CONFIG_RCU_NOCB_CPU_ALL
> + pr_info("\tOffload RCU callbacks from all CPUs\n");
> + cpumask_copy(rcu_nocb_mask, cpu_possible_mask);
> +#endif /* #ifdef CONFIG_RCU_NOCB_CPU_ALL */
> +#endif /* #ifndef CONFIG_RCU_NOCB_CPU_NONE */
> + if (have_rcu_nocb_mask) {
> + if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
> + pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
> + cpumask_and(rcu_nocb_mask, cpu_possible_mask,
> + rcu_nocb_mask);
> + }
> + cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
> + pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
> + if (rcu_nocb_poll)
> + pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
> + }
> +}
> +
> +/*
> * Check the RCU kernel configuration parameters and print informative
> * messages about anything out of the ordinary. If you like #ifdef, you
> * will love this function.
> @@ -86,32 +119,8 @@ static void __init rcu_bootup_announce_oddness(void)
> if (nr_cpu_ids != NR_CPUS)
> pr_info("\tRCU restricting CPUs from NR_CPUS=%d to nr_cpu_ids=%d.\n", NR_CPUS, nr_cpu_ids);
> #ifdef CONFIG_RCU_NOCB_CPU
Please also move the above #ifdef into rcu_bootup_announce_oddness_nocb().
The compiler will inline the resulting empty function, and it is cleaner
to have all of the NOCB-related #ifdefs in that function.
> -#ifndef CONFIG_RCU_NOCB_CPU_NONE
> - if (!have_rcu_nocb_mask) {
> - zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL);
> - have_rcu_nocb_mask = true;
> - }
> -#ifdef CONFIG_RCU_NOCB_CPU_ZERO
> - pr_info("\tOffload RCU callbacks from CPU 0\n");
> - cpumask_set_cpu(0, rcu_nocb_mask);
> -#endif /* #ifdef CONFIG_RCU_NOCB_CPU_ZERO */
> -#ifdef CONFIG_RCU_NOCB_CPU_ALL
> - pr_info("\tOffload RCU callbacks from all CPUs\n");
> - cpumask_copy(rcu_nocb_mask, cpu_possible_mask);
> -#endif /* #ifdef CONFIG_RCU_NOCB_CPU_ALL */
> -#endif /* #ifndef CONFIG_RCU_NOCB_CPU_NONE */
> - if (have_rcu_nocb_mask) {
> - if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
> - pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
> - cpumask_and(rcu_nocb_mask, cpu_possible_mask,
> - rcu_nocb_mask);
> - }
> - cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
> - pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
> - if (rcu_nocb_poll)
> - pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
> - }
> -#endif /* #ifdef CONFIG_RCU_NOCB_CPU */
> + rcu_bootup_announce_oddness_nocb();
> +#endif
> }
>
> #ifdef CONFIG_TREE_PREEMPT_RCU
> --
> 2.0.1
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 2/2] rcu: Check the return value of rcu_nocb_mask cpumask allocation
2014-07-25 15:25 ` Paul E. McKenney
@ 2014-07-25 18:06 ` Paul E. McKenney
2014-07-25 19:33 ` Pranith Kumar
0 siblings, 1 reply; 6+ messages in thread
From: Paul E. McKenney @ 2014-07-25 18:06 UTC (permalink / raw)
To: Pranith Kumar
Cc: Josh Triplett, Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan,
open list:READ-COPY UPDATE...
On Fri, Jul 25, 2014 at 08:25:51AM -0700, Paul E. McKenney wrote:
> On Thu, Jul 24, 2014 at 08:37:32PM -0400, Pranith Kumar wrote:
> > This commit checks the return value of the zalloc_cpumask_var() used for
> > allocating cpumask for rcu_nocb_mask.
> >
> > Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
>
> Hmmm... I saw the check in the previous patch, but didn't see removal
> of the later have_rcu_nocb_mask check. Please see below.
And events overtook this one. Turns out that commit b58cc46c5f6b
(rcu: Don't offload callbacks unless specifically requested) was not
one of my best efforts.
I will adapt your patch 2/2 in this series and apply it with your
Signed-off-by. Patch 1/2 is obsoleted by the current fix for
commit b58cc46c5f6b.
Thanx, Paul
> > ---
> > v2: no change from v1
> >
> > kernel/rcu/tree_plugin.h | 23 ++++++++++++-----------
> > 1 file changed, 12 insertions(+), 11 deletions(-)
> >
> > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> > index 520538a..9c9a01c 100644
> > --- a/kernel/rcu/tree_plugin.h
> > +++ b/kernel/rcu/tree_plugin.h
> > @@ -54,7 +54,10 @@ static void __init rcu_bootup_announce_oddness_nocb(void)
> > {
> > #ifndef CONFIG_RCU_NOCB_CPU_NONE
> > if (!have_rcu_nocb_mask) {
> > - zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL);
> > + if (!zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL)) {
> > + pr_info("rcu_nocb_mask allocation failed\n");
> > + return;
> > + }
> > have_rcu_nocb_mask = true;
> > }
> > #ifdef CONFIG_RCU_NOCB_CPU_ZERO
> > @@ -66,17 +69,15 @@ static void __init rcu_bootup_announce_oddness_nocb(void)
> > cpumask_copy(rcu_nocb_mask, cpu_possible_mask);
> > #endif /* #ifdef CONFIG_RCU_NOCB_CPU_ALL */
> > #endif /* #ifndef CONFIG_RCU_NOCB_CPU_NONE */
> > - if (have_rcu_nocb_mask) {
> > - if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
> > - pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
> > - cpumask_and(rcu_nocb_mask, cpu_possible_mask,
> > - rcu_nocb_mask);
> > - }
> > - cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
> > - pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
> > - if (rcu_nocb_poll)
> > - pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
> > + if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
>
> What happens if CONFIG_RCU_NOCB_CPU_NONE=y and the rcu_nocbs= boot
> parameter is not specified and we get here?
>
> In order to get visible failures when testing, build with
> CONFIG_CPUMASK_OFFSTACK=y.
>
> > + pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
> > + cpumask_and(rcu_nocb_mask, cpu_possible_mask,
> > + rcu_nocb_mask);
> > }
> > + cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
> > + pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
> > + if (rcu_nocb_poll)
> > + pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
> > }
> >
> > /*
> > --
> > 2.0.1
> >
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 2/2] rcu: Check the return value of rcu_nocb_mask cpumask allocation
2014-07-25 18:06 ` Paul E. McKenney
@ 2014-07-25 19:33 ` Pranith Kumar
0 siblings, 0 replies; 6+ messages in thread
From: Pranith Kumar @ 2014-07-25 19:33 UTC (permalink / raw)
To: Paul McKenney
Cc: Josh Triplett, Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan,
open list:READ-COPY UPDATE...
On Fri, Jul 25, 2014 at 2:06 PM, Paul E. McKenney
<paulmck@linux.vnet.ibm.com> wrote:
> On Fri, Jul 25, 2014 at 08:25:51AM -0700, Paul E. McKenney wrote:
>> On Thu, Jul 24, 2014 at 08:37:32PM -0400, Pranith Kumar wrote:
>> > This commit checks the return value of the zalloc_cpumask_var() used for
>> > allocating cpumask for rcu_nocb_mask.
>> >
>> > Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
>>
>> Hmmm... I saw the check in the previous patch, but didn't see removal
>> of the later have_rcu_nocb_mask check. Please see below.
>
> And events overtook this one. Turns out that commit b58cc46c5f6b
> (rcu: Don't offload callbacks unless specifically requested) was not
> one of my best efforts.
>
> I will adapt your patch 2/2 in this series and apply it with your
> Signed-off-by. Patch 1/2 is obsoleted by the current fix for
> commit b58cc46c5f6b.
>
OK. I am curious to see what problem you found in that commit.
I look forward to see your updated patch.
>> > ---
>> > v2: no change from v1
>> >
>> > kernel/rcu/tree_plugin.h | 23 ++++++++++++-----------
>> > 1 file changed, 12 insertions(+), 11 deletions(-)
>> >
>> > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
>> > index 520538a..9c9a01c 100644
>> > --- a/kernel/rcu/tree_plugin.h
>> > +++ b/kernel/rcu/tree_plugin.h
>> > @@ -54,7 +54,10 @@ static void __init rcu_bootup_announce_oddness_nocb(void)
>> > {
>> > #ifndef CONFIG_RCU_NOCB_CPU_NONE
>> > if (!have_rcu_nocb_mask) {
>> > - zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL);
>> > + if (!zalloc_cpumask_var(&rcu_nocb_mask, GFP_KERNEL)) {
>> > + pr_info("rcu_nocb_mask allocation failed\n");
>> > + return;
>> > + }
>> > have_rcu_nocb_mask = true;
>> > }
>> > #ifdef CONFIG_RCU_NOCB_CPU_ZERO
>> > @@ -66,17 +69,15 @@ static void __init rcu_bootup_announce_oddness_nocb(void)
>> > cpumask_copy(rcu_nocb_mask, cpu_possible_mask);
>> > #endif /* #ifdef CONFIG_RCU_NOCB_CPU_ALL */
>> > #endif /* #ifndef CONFIG_RCU_NOCB_CPU_NONE */
>> > - if (have_rcu_nocb_mask) {
>> > - if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
>> > - pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
>> > - cpumask_and(rcu_nocb_mask, cpu_possible_mask,
>> > - rcu_nocb_mask);
>> > - }
>> > - cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
>> > - pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
>> > - if (rcu_nocb_poll)
>> > - pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
>> > + if (!cpumask_subset(rcu_nocb_mask, cpu_possible_mask)) {
>>
>> What happens if CONFIG_RCU_NOCB_CPU_NONE=y and the rcu_nocbs= boot
>> parameter is not specified and we get here?
>>
>> In order to get visible failures when testing, build with
>> CONFIG_CPUMASK_OFFSTACK=y.
>>
>> > + pr_info("\tNote: kernel parameter 'rcu_nocbs=' contains nonexistent CPUs.\n");
>> > + cpumask_and(rcu_nocb_mask, cpu_possible_mask,
>> > + rcu_nocb_mask);
>> > }
>> > + cpulist_scnprintf(nocb_buf, sizeof(nocb_buf), rcu_nocb_mask);
>> > + pr_info("\tOffload RCU callbacks from CPUs: %s.\n", nocb_buf);
>> > + if (rcu_nocb_poll)
>> > + pr_info("\tPoll for callbacks from no-CBs CPUs.\n");
>> > }
>> >
>> > /*
>> > --
>> > 2.0.1
>> >
>
--
Pranith
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2014-07-25 19:34 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2014-07-25 0:37 [PATCH v2 1/2] rcu: Create a function for rcu_nocb_mask boot time setup Pranith Kumar
2014-07-25 0:37 ` [PATCH v2 2/2] rcu: Check the return value of rcu_nocb_mask cpumask allocation Pranith Kumar
2014-07-25 15:25 ` Paul E. McKenney
2014-07-25 18:06 ` Paul E. McKenney
2014-07-25 19:33 ` Pranith Kumar
2014-07-25 15:27 ` [PATCH v2 1/2] rcu: Create a function for rcu_nocb_mask boot time setup Paul E. McKenney
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox