From 1b815b89599cdd9b54e5aa70f5b97088225b2bcc Mon Sep 17 00:00:00 2001 From: Matthias Gatto Date: Tue, 21 Feb 2017 15:25:30 +0100 Subject: [PATCH] vhost: try to shrink pfdset when fdset_add fails fdset_add increments pfdset->num, but fdset_del doesn't decrement pfdset->num, so if we call fdset_add then fdset_del in a loop without calling fdset_shrink, we can easily exceed MAX_FDS with only a few number of fds used. So my solution is simply to call fdset_shrink in fdset_add when it exceeds MAX_FDS. Because fdset_shrink and fdset_add locks pfdset->fd_mutex we can't call fdset_shrink inside fdset_add because that would cause a dead lock, so this patch split fdset_shrink in two, fdset_shrink and fdset_shrink_nolock. Fixes: 59317cef249c ("vhost: allow many vhost-user ports") Cc: stable@dpdk.org Signed-off-by: Matthias Gatto --- lib/librte_vhost/fd_man.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/lib/librte_vhost/fd_man.c b/lib/librte_vhost/fd_man.c index 8a075da224..c7a4490d82 100644 --- a/lib/librte_vhost/fd_man.c +++ b/lib/librte_vhost/fd_man.c @@ -65,17 +65,12 @@ fdset_move(struct fdset *pfdset, int dst, int src) pfdset->rwfds[dst] = pfdset->rwfds[src]; } -/* - * Find deleted fd entries and remove them - */ static void -fdset_shrink(struct fdset *pfdset) +fdset_shrink_nolock(struct fdset *pfdset) { int i; int last_valid_idx = get_last_valid_idx(pfdset, pfdset->num - 1); - pthread_mutex_lock(&pfdset->fd_mutex); - for (i = 0; i < last_valid_idx; i++) { if (pfdset->fd[i].fd != -1) continue; @@ -84,7 +79,16 @@ fdset_shrink(struct fdset *pfdset) last_valid_idx = get_last_valid_idx(pfdset, last_valid_idx - 1); } pfdset->num = last_valid_idx + 1; +} +/* + * Find deleted fd entries and remove them + */ +static void +fdset_shrink(struct fdset *pfdset) +{ + pthread_mutex_lock(&pfdset->fd_mutex); + fdset_shrink_nolock(pfdset); pthread_mutex_unlock(&pfdset->fd_mutex); } @@ -151,8 +155,12 @@ fdset_add(struct fdset *pfdset, int fd, fd_cb rcb, fd_cb wcb, void *dat) pthread_mutex_lock(&pfdset->fd_mutex); i = pfdset->num < MAX_FDS ? pfdset->num++ : -1; if (i == -1) { - pthread_mutex_unlock(&pfdset->fd_mutex); - return -2; + fdset_shrink_nolock(pfdset); + i = pfdset->num < MAX_FDS ? pfdset->num++ : -1; + if (i == -1) { + pthread_mutex_unlock(&pfdset->fd_mutex); + return -2; + } } fdset_add_fd(pfdset, i, fd, rcb, wcb, dat); -- 2.20.1