Messages in this thread | | | Date | Thu, 22 Feb 2007 10:10:51 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] tty_io: fix race in master pty close/slave pty close path |
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Aristeu Sergio Rozanski Filho wrote: > > This normally would only issue a warning on idr_remove() but in case of a > customer's critical application, it's never too simple: > > thread1: opens master, gets index X > thread1: begin closing master > thread2: begin opening slave with index X > thread1: finishes closing master, index X released > thread3: opens master, gets index X, just released > thread2: fails opening slave, releases index X <---- > thread4: opens master, gets index X, init_dev() then find an already in use > and healthy tty and fails >
OK, that's fiendishly subtle, as most races are, of course. I'll try to walk through the codepaths to make sure the proposed patch doesn't introduce a leak, but the concept sounds good.
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