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authoraliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162>2008-10-31 17:24:21 +0000
committeraliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162>2008-10-31 17:24:21 +0000
commit1b435b10324fe9937f254bb00718f78d5e50837a (patch)
treedbde09a20acce19f528de2b0c156cae3bb708812 /hw/sun4m.c
parent474ad834d2c2637a7e5df527f8a89e2792b572ef (diff)
Make bottom halves more robust
Bottom halves are supposed to not complete until the next iteration of the main loop. This is very important to ensure that guests can not cause stack overflows in the block driver code. Right now, if you attempt to schedule a bottom half within a bottom half callback, you will enter an infinite loop. This patch uses the same logic that we use for the IOHandler loop to make the bottom half processing robust in list manipulation while in a callback. This patch also introduces idle scheduling for bottom halves. qemu_bh_poll() returns an indication of whether any bottom halves were successfully executed. qemu_aio_wait() uses this to immediately return if a bottom half was executed instead of waiting for a completion notification. qemu_bh_schedule_idle() works around this by not reporting the callback has run in the qemu_bh_poll loop. qemu_aio_wait() probably needs some refactoring but that would require a larger code audit. idle scheduling seems like a good compromise. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5572 c046a42c-6fe2-441c-8c8c-71466251a162
Diffstat (limited to 'hw/sun4m.c')
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