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. -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
