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 <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>
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 9cfedf5..fec2081 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -2337,7 +2337,7 @@
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 @@
sizeof(m->footer);
con->in_tag = CEPH_MSGR_TAG_READY;
con->in_seq++;
- return 0;
+ return 1;
}
BUG_ON(!con->in_msg);