From e7a88e82fe380459b864e05b372638aeacb0f52d Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Wed, 17 Feb 2016 20:04:08 +0100 Subject: [PATCH] libceph: don't bail early from try_read() when skipping a message The contract between try_read() and try_write() is that when called each processes as much data as possible. When instructed by osd_client to skip a message, try_read() is violating this contract by returning after receiving and discarding a single message instead of checking for more. try_write() then gets a chance to write out more requests, generating more replies/skips for try_read() to handle, forcing the messenger into a starvation loop. Cc: stable@vger.kernel.org # 3.10+ Reported-by: Varada Kari Signed-off-by: Ilya Dryomov Tested-by: Varada Kari Reviewed-by: Alex Elder --- net/ceph/messenger.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index 9cfedf565f5b..fec20819a5ea 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -2337,7 +2337,7 @@ static int read_partial_message(struct ceph_connection *con) con->in_base_pos = -front_len - middle_len - data_len - sizeof(m->footer); con->in_tag = CEPH_MSGR_TAG_READY; - return 0; + return 1; } else if ((s64)seq - (s64)con->in_seq > 1) { pr_err("read_partial_message bad seq %lld expected %lld\n", seq, con->in_seq + 1); @@ -2363,7 +2363,7 @@ static int read_partial_message(struct ceph_connection *con) sizeof(m->footer); con->in_tag = CEPH_MSGR_TAG_READY; con->in_seq++; - return 0; + return 1; } BUG_ON(!con->in_msg); -- 2.20.1