From: Ilya Dryomov Date: Wed, 17 Feb 2016 19:04:08 +0000 (+0100) Subject: libceph: don't bail early from try_read() when skipping a message X-Git-Tag: Ubuntu-snapdragon-4.4.0-1050.54~5039 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=2ab7240e6573b475307b989b3b1d0b011f3a1120;p=mirror_ubuntu-artful-kernel.git libceph: don't bail early from try_read() when skipping a message BugLink: http://bugs.launchpad.net/bugs/1553179 commit e7a88e82fe380459b864e05b372638aeacb0f52d upstream. 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. Reported-by: Varada Kari Signed-off-by: Ilya Dryomov Tested-by: Varada Kari Reviewed-by: Alex Elder Signed-off-by: Greg Kroah-Hartman Signed-off-by: Tim Gardner --- diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index a145180150ef..93e3083f4006 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -2340,7 +2340,7 @@ 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); @@ -2366,7 +2366,7 @@ 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);