linux.kernel - 26 new messages in 16 topics - digest

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Today's topics:

* cpufreq: Fix timer/workqueue corruption by protecting reading governor_
enabled - 2 messages, 2 authors
http://groups.google.com/group/linux.kernel/t/1e2d65b016fd7b58?hl=en
* net: igbvf: slight optimization of addr compare - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/6552e236459e977b?hl=en
* ARM: omapfb: Add early framebuffer memory allocator - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/27241acfc4476030?hl=en
* mm/slub: fix accumulate per cpu partial cache objects - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/0cb324ae47631dd0?hl=en
* net: ixgbe: slight optimization of addr compare - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/83939ed7941c486a?hl=en
* Staging: tidspbridge: Use hashtable implementation - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/eef76bdd56cd4229?hl=en
* Add the LED burst trigger - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/62d67318b99b0ab1?hl=en
* cpufreq: try to resume policies which failed on last resume - 2 messages, 1
author
http://groups.google.com/group/linux.kernel/t/a84d5003d1ec65b6?hl=en
* perf tools: Make the print_pmu_events funtion to return unsigned int. - 9
messages, 1 author
http://groups.google.com/group/linux.kernel/t/003bb3b209f00698?hl=en
* serial: samsung: Remove hard-coded major/minor numbers - 1 messages, 1
author
http://groups.google.com/group/linux.kernel/t/84254284a552fbb4?hl=en
* nouveau nvaa clock missing break? - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/e4e1f1e1869b3f36?hl=en
* sched/auto_group: fix consume memory even if add 'noautogroup' in the
cmdline - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/4431597ed3bca8be?hl=en
* mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE - 1 messages, 1
author
http://groups.google.com/group/linux.kernel/t/06781e5804983c0b?hl=en
* aio: optimize free kioctx slot search - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/4a80a4002f16c63b?hl=en
* filesystems: Update 00-INDEX in Documentation/filesystems - 1 messages, 1
author
http://groups.google.com/group/linux.kernel/t/129d66005f795245?hl=en
* f2fs: fix build warning for f2fs_has_inline_data() - 1 messages, 1 author
http://groups.google.com/group/linux.kernel/t/9277437d2e9a5bac?hl=en

==============================================================================
TOPIC: cpufreq: Fix timer/workqueue corruption by protecting reading governor_
enabled
http://groups.google.com/group/linux.kernel/t/1e2d65b016fd7b58?hl=en
==============================================================================

== 1 of 2 ==
Date: Fri, Dec 27 2013 1:40 am
From:


From: Jane Li <jiel@marvell.com>

When a CPU is hot removed we'll cancel all the delayed work items via
gov_cancel_work(). Sometimes the delayed work function determines that
it should adjust the delay for all other CPUs that the policy is
managing. If this scenario occurs, the canceling CPU will cancel its own
work but queue up the other CPUs works to run.

Commit 3617f2(cpufreq: Fix timer/workqueue corruption due to double
queueing) has tried to fix this, but reading governor_enabled is not
protected by cpufreq_governor_lock. Even though od_dbs_timer() checks
governor_enabled before gov_queue_work(), this scenario may occur. For
example:

CPU0 CPU1
---- ----
cpu_down()
... <work runs>
__cpufreq_remove_dev() od_dbs_timer()
__cpufreq_governor() policy->governor_enabled
policy->governor_enabled = false;
cpufreq_governor_dbs()
case CPUFREQ_GOV_STOP:
gov_cancel_work(dbs_data, policy);
cpu0 work is canceled
timer is canceled
cpu1 work is canceled
<waits for cpu1>
gov_queue_work(*, *, true);
cpu0 work queued
cpu1 work queued
cpu2 work queued
...
cpu1 work is canceled
cpu2 work is canceled
...

At the end of the GOV_STOP case cpu0 still has a work queued to
run although the code is expecting all of the works to be
canceled. __cpufreq_remove_dev() will then proceed to
re-initialize all the other CPUs works except for the CPU that is
going down. The CPUFREQ_GOV_START case in cpufreq_governor_dbs()
will trample over the queued work and debugobjects will spit out
a warning:

WARNING: at lib/debugobjects.c:260 debug_print_object+0x94/0xbc()
ODEBUG: init active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x14
Modules linked in:
CPU: 1 PID: 1205 Comm: sh Tainted: G W 3.10.0 #200
[<c01144f0>] (unwind_backtrace+0x0/0xf8) from [<c0111d98>] (show_stack+0x10/0x14)
[<c0111d98>] (show_stack+0x10/0x14) from [<c01272cc>] (warn_slowpath_common+0x4c/0x68)
[<c01272cc>] (warn_slowpath_common+0x4c/0x68) from [<c012737c>] (warn_slowpath_fmt+0x30/0x40)
[<c012737c>] (warn_slowpath_fmt+0x30/0x40) from [<c034c640>] (debug_print_object+0x94/0xbc)
[<c034c640>] (debug_print_object+0x94/0xbc) from [<c034c7f8>] (__debug_object_init+0xc8/0x3c0)
[<c034c7f8>] (__debug_object_init+0xc8/0x3c0) from [<c01360e0>] (init_timer_key+0x20/0x104)
[<c01360e0>] (init_timer_key+0x20/0x104) from [<c04872ac>] (cpufreq_governor_dbs+0x1dc/0x68c)
[<c04872ac>] (cpufreq_governor_dbs+0x1dc/0x68c) from [<c04833a8>] (__cpufreq_governor+0x80/0x1b0)
[<c04833a8>] (__cpufreq_governor+0x80/0x1b0) from [<c0483704>] (__cpufreq_remove_dev.isra.12+0x22c/0x380)
[<c0483704>] (__cpufreq_remove_dev.isra.12+0x22c/0x380) from [<c0692f38>] (cpufreq_cpu_callback+0x48/0x5c)
[<c0692f38>] (cpufreq_cpu_callback+0x48/0x5c) from [<c014fb40>] (notifier_call_chain+0x44/0x84)
[<c014fb40>] (notifier_call_chain+0x44/0x84) from [<c012ae44>] (__cpu_notify+0x2c/0x48)
[<c012ae44>] (__cpu_notify+0x2c/0x48) from [<c068dd40>] (_cpu_down+0x80/0x258)
[<c068dd40>] (_cpu_down+0x80/0x258) from [<c068df40>] (cpu_down+0x28/0x3c)
[<c068df40>] (cpu_down+0x28/0x3c) from [<c068e4c0>] (store_online+0x30/0x74)
[<c068e4c0>] (store_online+0x30/0x74) from [<c03a7308>] (dev_attr_store+0x18/0x24)
[<c03a7308>] (dev_attr_store+0x18/0x24) from [<c0256fe0>] (sysfs_write_file+0x100/0x180)
[<c0256fe0>] (sysfs_write_file+0x100/0x180) from [<c01fec9c>] (vfs_write+0xbc/0x184)
[<c01fec9c>] (vfs_write+0xbc/0x184) from [<c01ff034>] (SyS_write+0x40/0x68)
[<c01ff034>] (SyS_write+0x40/0x68) from [<c010e200>] (ret_fast_syscall+0x0/0x48)

In gov_queue_work(), lock cpufreq_governor_lock before gov_queue_work,
and unlock it after __gov_queue_work(). In this way, governor_enabled
is guaranteed not changed in gov_queue_work().

Signed-off-by: Jane Li <jiel@marvell.com>
---
drivers/cpufreq/cpufreq.c | 1 -
drivers/cpufreq/cpufreq_governor.c | 6 +++++-
include/linux/cpufreq.h | 1 +
3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 02d534d..50601f6 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -39,7 +39,6 @@ static struct cpufreq_driver *cpufreq_driver;
static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data_fallback);
static DEFINE_RWLOCK(cpufreq_driver_lock);
-static DEFINE_MUTEX(cpufreq_governor_lock);
static LIST_HEAD(cpufreq_policy_list);

#ifdef CONFIG_HOTPLUG_CPU
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index e6be635..11b9f0b 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -119,8 +119,11 @@ void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy,
{
int i;

- if (!policy->governor_enabled)
+ mutex_lock(&cpufreq_governor_lock);
+ if (!policy->governor_enabled) {
+ mutex_unlock(&cpufreq_governor_lock);
return;
+ }

if (!all_cpus) {
/*
@@ -135,6 +138,7 @@ void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy,
for_each_cpu(i, policy->cpus)
__gov_queue_work(i, dbs_data, delay);
}
+ mutex_unlock(&cpufreq_governor_lock);
}
EXPORT_SYMBOL_GPL(gov_queue_work);

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index dc196bb..4faafe7 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -254,6 +254,7 @@ struct cpufreq_driver {

int cpufreq_register_driver(struct cpufreq_driver *driver_data);
int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
+static DEFINE_MUTEX(cpufreq_governor_lock);

const char *cpufreq_get_current_driver(void);

--
1.7.9.5

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== 2 of 2 ==
Date: Fri, Dec 27 2013 1:50 am
From: Viresh Kumar


On 27 December 2013 15:00, <jiel@marvell.com> wrote:
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> -static DEFINE_MUTEX(cpufreq_governor_lock);

> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index dc196bb..4faafe7 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -254,6 +254,7 @@ struct cpufreq_driver {
>
> int cpufreq_register_driver(struct cpufreq_driver *driver_data);
> int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
> +static DEFINE_MUTEX(cpufreq_governor_lock);

No way, this would never work. This would create separate locks
in each file that includes cpufreq.h. And so the locks you are talking
about wouldn't protect governor.

Have you actually tested this code? If this fixes the breakage you
saw? If this fixes it then you need to do better investigation of your
problem..

you actually need to remove the static keyword from cpufreq.c file.
Nothing else.
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==============================================================================
TOPIC: net: igbvf: slight optimization of addr compare
http://groups.google.com/group/linux.kernel/t/6552e236459e977b?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Dec 27 2013 1:50 am
From: Jeff Kirsher


On Fri, 2013-12-27 at 14:48 +0800, Ding Tianhong wrote:
> Use possibly more efficient ether_addr_equal
> to instead of memcmp.
>
> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
> Cc: Carolyn Wyborny <carolyn.wyborny@intel.com>
> Cc: Don Skidmore <donald.c.skidmore@intel.com>
> Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
> ---
> drivers/net/ethernet/intel/igbvf/netdev.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Thanks Ding, I have added this patch to my queue.





==============================================================================
TOPIC: ARM: omapfb: Add early framebuffer memory allocator
http://groups.google.com/group/linux.kernel/t/27241acfc4476030?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Dec 27 2013 1:50 am
From: Pavel Machek


On Thu 2013-12-26 01:12:39, Ivaylo Dimitrov wrote:
> From: Ivaylo Dimitrov <freemangordon@abv.bg>
>
> On memory limited devices, CMA fails easily when asked to allocate big
> chunks of memory like framebuffer memory needed for video playback.
>
> Add boot parameter "omapfb_memsize" which allocates memory to be used
> as dma coherent memory, so dma_alloc_attrs won't hit CMA allocator when
> trying to allocate memory for the framebuffers
>
> Signed-off-by: Ivaylo Dimitrov <freemangordon@abv.bg>

Hmm, would it make sense to add a parameter to reserve certain ammount
of memory for CMA? omapfb is probably not the only user hitting
this...?
Pavel
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==============================================================================
TOPIC: mm/slub: fix accumulate per cpu partial cache objects
http://groups.google.com/group/linux.kernel/t/0cb324ae47631dd0?hl=en
==============================================================================

== 1 of 1 ==
Date: Fri, Dec 27 2013 1:50 am
From: Wanpeng Li


SLUB per cpu partial cache is a list of slab caches to accelerate objects
allocation. However, current codes just accumulate the objects number of
the first slab cache of per cpu partial cache instead of traverse the whole
list.

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
---
mm/slub.c | 32 +++++++++++++++++++++++---------
1 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 545a170..799bfdc 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4280,7 +4280,7 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab,
cpu);
int node;
- struct page *page;
+ struct page *page, *p;

page = ACCESS_ONCE(c->page);
if (!page)
@@ -4298,8 +4298,9 @@ static ssize_t show_slab_objects(struct kmem_cache *s,
nodes[node] += x;

page = ACCESS_ONCE(c->partial);
- if (page) {
- x = page->pobjects;
+ while ((p = page)) {
+ page = p->next;
+ x = p->pobjects;
total += x;
nodes[node] += x;
}
@@ -4520,13 +4521,15 @@ static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
int pages = 0;
int cpu;
int len;
+ struct page *p;

for_each_online_cpu(cpu) {
struct page *page = per_cpu_ptr(s->cpu_slab, cpu)->partial;

- if (page) {
- pages += page->pages;
- objects += page->pobjects;
+ while ((p = page)) {
+ page = p->next;
+ pages += p->pages;
+ objects += p->pobjects;
}
}

@@ -4535,10 +4538,21 @@ static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
#ifdef CONFIG_SMP
for_each_online_cpu(cpu) {
struct page *page = per_cpu_ptr(s->cpu_slab, cpu) ->partial;
+ objects = 0;
+ pages = 0;
+
+ if (!page)
+ continue;
+
+ while ((p = page)) {
+ page = p->next;
+ pages += p->pages;
+ objects += p->pobjects;
+ }

- if (page && len < PAGE_SIZE - 20)
- len += sprintf(buf + len, " C%d=%d(%d)", cpu,
- page->pobjects, page->pages);
+ if (len < PAGE_SIZE - 20)
+ len += sprintf(buf + len, " C%d=%d(%d)", cpu,
+ objects, pages);
}