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SubjectRe: Linux 2.6.21-rc5
On Wed, 28 Mar 2007, Michal Piotrowski wrote:

> BUG: using smp_processor_id() in preemptible [00000001] code: mount/7245
> is fixed, thanks.
> but I still get this
> [ 208.523901] =================================
> [ 208.529739] [ INFO: inconsistent lock state ]
> [ 208.534087] 2.6.21-rc5-g28defbea-dirty #131
> [ 208.538260] ---------------------------------
> [ 208.542611] inconsistent {hardirq-on-W} -> {in-hardirq-W} usage.
> [ 208.548600] swapper/0 [HC1[1]:SC0[0]:HE0:SE1] takes:

Perhaps something like the one below?


From: Jiri Kosina <jkosina@suse.cz>

oprofile: fix potential deadlock on oprofilefs_lock

nmi_cpu_setup() is called from hardirq context and acquires oprofilefs_lock.
alloc_event_buffer() and oprofilefs_ulong_from_user() acquire this lock
without disabling irqs, which could deadlock.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/oprofile/event_buffer.c | 5 +++--
drivers/oprofile/oprofilefs.c | 5 +++--
2 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/oprofile/event_buffer.c b/drivers/oprofile/event_buffer.c
index 00e937e..e7fbac5 100644
--- a/drivers/oprofile/event_buffer.c
+++ b/drivers/oprofile/event_buffer.c
@@ -70,11 +70,12 @@ void wake_up_buffer_waiter(void)
int alloc_event_buffer(void)
{
int err = -ENOMEM;
+ unsigned long flags;

- spin_lock(&oprofilefs_lock);
+ spin_lock_irqsave(&oprofilefs_lock, flags);
buffer_size = fs_buffer_size;
buffer_watershed = fs_buffer_watershed;
- spin_unlock(&oprofilefs_lock);
+ spin_unlock_irqrestore(&oprofilefs_lock, flags);

if (buffer_watershed >= buffer_size)
return -EINVAL;
diff --git a/drivers/oprofile/oprofilefs.c b/drivers/oprofile/oprofilefs.c
index 6e67b42..8543cb2 100644
--- a/drivers/oprofile/oprofilefs.c
+++ b/drivers/oprofile/oprofilefs.c
@@ -65,6 +65,7 @@ ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user * buf, size_t co
int oprofilefs_ulong_from_user(unsigned long * val, char const __user * buf, size_t count)
{
char tmpbuf[TMPBUFSIZE];
+ unsigned long flags;

if (!count)
return 0;
@@ -77,9 +78,9 @@ int oprofilefs_ulong_from_user(unsigned long * val, char const __user * buf, siz
if (copy_from_user(tmpbuf, buf, count))
return -EFAULT;

- spin_lock(&oprofilefs_lock);
+ spin_lock_irqsave(&oprofilefs_lock, flags);
*val = simple_strtoul(tmpbuf, NULL, 0);
- spin_unlock(&oprofilefs_lock);
+ spin_unlock_irqrestore(&oprofilefs_lock, flags);
return 0;
}

-
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