On Tue, 6 Jan 2004, Don Lewis wrote: > [... lots of good stuff] > I found another bug, though. Holding a mutex across a malloc() call is > not allowed because malloc() can sleep, and sleeping while holding a > mutex is not allowed. sndbuf_resize() sndbuf_remalloc() both call > malloc() to allocate buffers, and sndbuf_alloc() and sndbuf_setup() call > sndbuf_resize(). The problem is that chn_setblocksize() calls > sndbuf_remalloc() while the channel mutex is held. We can't just unlock > the mutex around the sndbuf_remalloc() call because the channel > interrupt service routine could run while the buffer is being > re-allocated. It would be best if the channel were to be shut down when > re-allocating the buffer. This is likely to be messy since > chn_setblocksize() is called from lots of different places. Er, its an M_NOWAIT malloc(), so it can't sleep. M_WAITOK malloc()s in interrupt handlers would also be bugs, but that is not a problem here for the same reason. There should be more checks for potential sleeps while holding a mutex. BruceReceived on Tue Jan 06 2004 - 23:15:58 UTC
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