From 648fb0ea5e9d7f32c80ec23c3ece4321403dfecd Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Thu, 1 Sep 2011 16:16:10 +0200 Subject: async: Allow nested qemu_bh_poll calls qemu may segfault when a BH handler first deletes a BH and then (possibly indirectly) calls a nested qemu_bh_poll(). This is because the inner instance frees the BH and deletes it from the list that the outer one processes. This patch deletes BHs only in the outermost qemu_bh_poll instance. Commit 7887f620 already tried to achieve the same, but it assumed that the BH handler would only delete its own BH. With a nested qemu_bh_poll(), this isn't guaranteed, so that commit wasn't enough. Hope this one fixes it for real. Signed-off-by: Kevin Wolf --- async.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) (limited to 'async.c') diff --git a/async.c b/async.c index 9d4e960b0..ca1396222 100644 --- a/async.c +++ b/async.c @@ -55,6 +55,9 @@ int qemu_bh_poll(void) { QEMUBH *bh, **bhp, *next; int ret; + static int nesting = 0; + + nesting++; ret = 0; for (bh = first_bh; bh; bh = next) { @@ -68,15 +71,20 @@ int qemu_bh_poll(void) } } + nesting--; + /* remove deleted bhs */ - bhp = &first_bh; - while (*bhp) { - bh = *bhp; - if (bh->deleted) { - *bhp = bh->next; - g_free(bh); - } else - bhp = &bh->next; + if (!nesting) { + bhp = &first_bh; + while (*bhp) { + bh = *bhp; + if (bh->deleted) { + *bhp = bh->next; + g_free(bh); + } else { + bhp = &bh->next; + } + } } return ret; -- cgit v1.2.3