You can (and should) manipulate _spinlocks_ in interrupt context. You cannot touch _semaphores_ nor do anything that would imply a sleep. BHs run with interrupts enabled and thus allow for longer processing as opposed to an interrupt handler which must execute as fast as possible. Florin -----Original Message----- From: kernelnewbies-bounce@nl.linux.org [mailto:kernelnewbies-bounce@nl.linux.org] On Behalf Of Zeeshan Ali Sent: Thursday, March 04, 2004 3:40 PM To: kernelnewbies@nl.linux.org Subject: Whats bottom halfs for then? Hello, I needed to do some thing in an interrupt for which it is necessary to lock on a spinlock. As this could'nt/should'nt be done in an interrupt, I looked at bottom halfs, but I was shocked to see this written in Linux Device Drivers, 2nd ed.: "One thing to keep in mind with bottom-half processing is that all of the restrictions that apply to interrupt handlers also apply to bottom halves. Thus, bottom halves cannot sleep, cannot access user space, and cannot invoke the scheduler." Please give some guidance. ===== "The whole problem with the world is that fools and fanatics are always so certain of themselves, but wiser people so full of doubts." --Bertrand Russell "We are convinced that freedom without Socialism is privilege and injustice, and that Socialism without freedom is slavery and brutality." from the book: "The Political Philosophy of Bakunin". __________________________________ Do you Yahoo!? Yahoo! Search - Find what you're looking for faster http://search.yahoo.com -- 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/
