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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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      Last update: 2007-03-28 18:15    [W:0.058 / U:30.476 seconds]
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