Hi Rodolfo,
On Sun, 29 Jul 2007, Rodolfo Giometti wrote: > On Sat, Jul 28, 2007 at 05:11:17AM +0530, Satyam Sharma wrote: > > > Take the race between the time_pps_setparams() syscall and a concurrent > > pps_event() from an interrupt for instance. From sys_time_pps_setparams, > > the parameters for an existing source are not modified / set atomically, > > which means a pps_event() called on the same source in between will see > > invalid parameters ... and bad things will happen. > > I think this should be a good solution... :) > > diff --git a/drivers/pps/kapi.c b/drivers/pps/kapi.c > index 08de71d..f0c42ec 100644 > --- a/drivers/pps/kapi.c > +++ b/drivers/pps/kapi.c > @@ -29,12 +29,6 @@ > #include <linux/pps.h> > > /* > - * Local variables > - */ > - > -static spinlock_t pps_lock = SPIN_LOCK_UNLOCKED; > - > -/* > * Local functions > */ > > diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c > index 9176c01..91b7e4d 100644 > --- a/drivers/pps/pps.c > +++ b/drivers/pps/pps.c > @@ -35,6 +35,7 @@ > > struct pps_s pps_source[PPS_MAX_SOURCES]; > DEFINE_MUTEX(pps_mutex); > +spinlock_t pps_lock = SPIN_LOCK_UNLOCKED; > > /* > * Misc functions > @@ -227,6 +228,8 @@ asmlinkage long sys_time_pps_setparams(int source, > goto sys_time_pps_setparams_exit; > } > > + spin_lock(&pps_lock); > + > /* Save the new parameters */ > ret = copy_from_user(&pps_source[source].params, params, > sizeof(struct pps_kparams)); > @@ -245,6 +248,8 @@ asmlinkage long sys_time_pps_setparams(int source, > pps_source[source].params.mode |= PPS_CANWAIT; > pps_source[source].params.api_version = PPS_API_VERS; > > + spin_unlock(&pps_lock); > + > sys_time_pps_setparams_exit: > mutex_unlock(&pps_mutex); Nopes, this isn't quite correct/safe. I suggest you should read: http://www.kernel.org/pub/linux/kernel/people/rusty/kernel-locking/ Satyam - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/