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| author | Ilya Dryomov <idryomov@gmail.com> | 2016-02-17 20:04:08 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-03-03 15:06:53 -0800 |
| commit | 739ed1f0c0d26230e686fa12a1b1601b27471723 (patch) | |
| tree | e64d7e396a9bae07dbbb40502859fb8e98833c67 | |
| parent | 2b522d5f634ec22e24ca4470b54bb145324422f2 (diff) | |
| download | lwn-739ed1f0c0d26230e686fa12a1b1601b27471723.tar.gz lwn-739ed1f0c0d26230e686fa12a1b1601b27471723.zip | |
libceph: don't bail early from try_read() when skipping a message
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/ceph/messenger.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index 2e87eecec8f6..04dd542697a7 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -2279,7 +2279,7 @@ 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); @@ -2312,7 +2312,7 @@ 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); |