Thank you all for clarification. ~psr On 4/11/07, sandeep lahane <sandeep.lahane@xxxxxxxxx> wrote:
On 4/11/07, sandeep lahane <sandeep.lahane@xxxxxxxxx> wrote: > On 4/11/07, Gaurav Dhiman <gaurav.dhiman@xxxxxxxxxxx> wrote: > > > > > > > > ________________________________ > > From: kernelnewbies-bounce@xxxxxxxxxxxx 代理 Rajat Jain > > Sent: 4/11/2007 (水) 10:18 午前 > > To: pradeep singh > > Cc: kernelnewbies@xxxxxxxxxxxxxxxxx > > Subject: Re: recursive locks in linux > > > > > > > > > > On 4/11/07, pradeep singh <2500.pradeep@xxxxxxxxx> wrote: > > > Hi All, > > > This may sound stupid but how can i implement a recursive lock in Linux > > kernel? > > > I guess Mutex and semaphores cannot be used. > > > > > > Spinlocks can be i guess. > > > Can somebody give me some pointers or links for this? > > > Googling didn't help much. > > > > Spinlocks, semaphores & Mutexes defnitely can't be used. > > > > Although the RW semaphores and RW spinlocks allow recursive locking > > (since multiple threads can simultaneously hold reader locks). > > > > > > --------------- response from Gaurav Dhiman starts ----------------------- > > > > Rajat read-write locks are not recursive in nature, as the same thread can > > not again acquire the lock once it has already acquired the lock. There are > > no recursive lock avaialble and should not be avialable, as recursive locks > > lead to deadlock. When thread tries to acquire the lock for second time > > recursively, it will be put on hold or spin forever waiting for the lock to > > be release which the thread has itself acquired, leading it to deadlock. > > > > regards, > > > > Gaurav > > ------------------- response from Gaurav Dhiman ends -------------------- > > > > > > Just curious, why do you need it? > > > > Thanks, > > > > Rajat > > > > > > > > > > Thank you > > > > > > ~psr > > > > > > -- > > > play the game > > > > > > -- > > > To unsubscribe from this list: send an email with > > > "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx > > > Please read the FAQ at http://kernelnewbies.org/FAQ > > > > > > > > > > -- > > To unsubscribe from this list: send an email with > > "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx > > Please read the FAQ at http://kernelnewbies.org/FAQ > > > > > > AFAIK, only the BKL (big kernel lock) is spinning and recursive in > nature, but its use is discouraged. Please google to know why it > should not be used in case you dont know. > -- > > Regards, > Sandeep. > Or just look following topic in LDD3 5.6.3. Fine- Versus Coarse-Grained Locking -- Regards, Sandeep.
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