Messages in this thread Patch in this message | | | From | Kamal Mostafa <> | Subject | [PATCH 4.2.y-ckt 203/273] libceph: don't bail early from try_read() when skipping a message | Date | Mon, 7 Mar 2016 14:49:54 -0800 |
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4.2.8-ckt5 -stable review patch. If anyone has any objections, please let me know.
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From: Ilya Dryomov <idryomov@gmail.com>
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 <Varada.Kari@sandisk.com> Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Tested-by: Varada Kari <Varada.Kari@sandisk.com> Reviewed-by: Alex Elder <elder@linaro.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- 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 ec564c5..1d47fa3 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -2328,7 +2328,7 @@ 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); @@ -2361,7 +2361,7 @@ 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); -- 2.7.0
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