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SubjectRe: [PATCH 1/2] pm_qos: remove BKL
On Thu, Aug 06, 2009 at 01:59:53PM -0600, Jonathan Corbet wrote:
> pm_qos_power_open got its lock_kernel() calls from the open() pushdown. A
> look at the code shows that the only global resources accessed are
> pm_qos_array and "name". pm_qos_array doesn't change (things pointed to
> therein do change, but they are atomics and/or are protected by
> pm_qos_lock). Accesses to "name" are totally unprotected with or without
> the BKL; that will be fixed shortly. The BKL is not helpful here; take it
> out.
>
> Signed-off-by: Jonathan Corbet <corbet@lwn.net>


Is there a 2/2 missing patch in the series, or may be I missed it.
I guess it fixes the racy "name"...


> ---
> kernel/pm_qos_params.c | 8 +-------
> 1 files changed, 1 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
> index dfdec52..d96b83e 100644
> --- a/kernel/pm_qos_params.c
> +++ b/kernel/pm_qos_params.c
> @@ -29,7 +29,6 @@
>
> #include <linux/pm_qos_params.h>
> #include <linux/sched.h>
> -#include <linux/smp_lock.h>
> #include <linux/spinlock.h>
> #include <linux/slab.h>
> #include <linux/time.h>
> @@ -352,20 +351,15 @@ static int pm_qos_power_open(struct inode *inode, struct file *filp)
> int ret;
> long pm_qos_class;
>
> - lock_kernel();
> pm_qos_class = find_pm_qos_object_by_minor(iminor(inode));
> if (pm_qos_class >= 0) {
> filp->private_data = (void *)pm_qos_class;
> sprintf(name, "process_%d", current->pid);
> ret = pm_qos_add_requirement(pm_qos_class, name,
> PM_QOS_DEFAULT_VALUE);
> - if (ret >= 0) {
> - unlock_kernel();
> + if (ret >= 0)
> return 0;
> - }
> }
> - unlock_kernel();
> -
> return -EPERM;
> }
>
> --
> 1.6.2.5
>
> --
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