---------- Forwarded message ---------- From: Anand H. Krishnan <anandhkrishnan@xxxxxxxxx> Date: Sep 7, 2006 12:31 PM Subject: Re: sleeping in block device driver To: Fawad Lateef <fawadlateef@xxxxxxxxx> Hi,
> Here, the transfer is not done in process context, and > sbull_transfer() cannot sleep. How could I implement a sleeping > transfer? > The request function of block devices are called in process context and they can sleep (but end_io is called in interrupt context).
I think that you can sleep, provided 1) You release the request queue lock 2) You can accept the fact that because of your sleeping some other block device may get affected (kblockd workqueue...) which is not advisable.. Anand
Although in above example sbull_transfer is done in atomic context and only doing memory transfer not the real IO operation. So you can do sleep before or after transfering the data or simple use kmap and then can go into sleep during transfer. > char drivers can sleep and receive data fetched in an irq context, can > I not do this for block drivers? > Sorry I won't able to understand your question, but I can say that you can sleep in process context whether its char or block driver but if you got/receive data in irq context either in block or char driver you can sleep in that context rather can insert the data in a queue and just return from irq context; later use queued data in process context. I hope this helps. -- Fawad Lateef -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
-- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
