• Miklos Szeredi's avatar
    fuse: allow interrupt queuing without fc->lock · 8f7bb368
    Miklos Szeredi authored
    Interrupt is only queued after the request has been sent to userspace.
    This is either done in request_wait_answer() or fuse_dev_do_read()
    depending on which state the request is in at the time of the interrupt.
    If it's not yet sent, then queuing the interrupt is postponed until the
    request is read.  Otherwise (the request has already been read and is
    waiting for an answer) the interrupt is queued immedidately.
    
    We want to call queue_interrupt() without fc->lock protection, in which
    case there can be a race between the two functions:
    
     - neither of them queue the interrupt (thinking the other one has already
       done it).
    
     - both of them queue the interrupt
    
    The first one is prevented by adding memory barriers, the second is
    prevented by checking (under fiq->waitq.lock) if the interrupt has already
    been queued.
    Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
    8f7bb368
dev.c 51.6 KB