-----Original Message----- From: Julian Calaby [mailto:[email protected]] Sent: Monday, September 15, 2014 11:32 AM To: Sharma, Sanjeev Cc: Johannes Berg; [email protected]; [email protected]; [email protected]; [email protected]; [email protected] Subject: Re: [PATCH v2] zd1211rw: replace ZD_ASSERT with lockdep_assert_held()
Hi Sanjeev, On Thu, Sep 11, 2014 at 8:36 PM, Sharma, Sanjeev <[email protected]> wrote: > -----Original Message----- > From: Johannes Berg [mailto:[email protected]] > Sent: Thursday, September 11, 2014 3:42 PM > To: Sharma, Sanjeev > Cc: [email protected]; [email protected]; > [email protected]; [email protected]; > [email protected] > Subject: Re: [PATCH v2] zd1211rw: replace ZD_ASSERT with > lockdep_assert_held() > > On Thu, 2014-09-11 at 15:39 +0530, Sanjeev Sharma wrote: >> on some architecture spin_is_locked() always return false in >> uniprocessor configuration and therefore it would be advise to >> replace with lockdep_assert_held(). >> >> Signed-off-by: Sanjeev Sharma <[email protected]> >> --- >> Changes in v2: >> - corrected the typo > >> Now it compiles, but you got the logic wrong. > >> +++ b/drivers/net/wireless/zd1211rw/zd_mac.c >> @@ -235,7 +235,7 @@ void zd_mac_clear(struct zd_mac *mac) { >> flush_workqueue(zd_workqueue); >> zd_chip_clear(&mac->chip); >> - ZD_ASSERT(!spin_is_locked(&mac->lock)); >> + lockdep_assert_held(&mac->lock); >> ZD_MEMCLEAR(mac, sizeof(struct zd_mac)); } > >>Look closely at this again. > > I didn't understand where I put wrong logic ? I find it helps to spell out what code is doing in words. E.g. the line you're removing is: ZD_ASSERT(!spin_is_locked(&mac->lock)); So, we'll assert when spin_is_locked(&mac->lock) is false, i.e. when mac->lock is not spin locked. This isn't the same as what you're replacing it with. I feel logic is absolutely correct and if you expand it will looks like .. +#define lockdep_assert_held(l) do { \ + WARN_ON(debug_locks && !lockdep_is_held(l)); \ + } while (0) Please refer http://lkml.iu.edu/hypermail/linux/kernel/1203.2/00369.html and also see include/linux/lockdep.h for more detail. Thanks Sanjeev Sharma
