[Libguestfs] [libnbd PATCH 1/2] lib: Decrement in_flight at response, not retirement

We had a mismatch between documentation/code comments (nbd_aio_in_flight counts commands not yet ready to retire) and actual code (we didn't decrement the count until nbd_aio_command_completed). As the documented behavior is useful (I shouldn't delay sending a command to the server merely because I haven't retired all the available commands), it is worth fixing the code to match the intent. This also means decrementing in_flight in bulk when commands are stranded due to a transition to CLOSED/DEAD. Update the testsuite to cover this. Fixes: a05b2237 --- generator/states-reply.c | 2 ++ generator/states.c | 2 ++ lib/aio.c | 2 -- tests/server-death.c | 10 +++++----- 4 files changed, 9 insertions(+), 7 deletions(-) diff --git a/generator/states-reply.c b/generator/states-reply.c index 05b2e58..4b22c39 100644 --- a/generator/states-reply.c +++ b/generator/states-reply.c @@ -179,6 +179,8 @@ save_reply_state (struct nbd_handle *h) } else h->cmds_done = cmd; + h->in_flight--; + assert (h->in_flight >= 0); /* Notify the user */ if (cmd->cb.callback) { diff --git a/generator/states.c b/generator/states.c index fa6df9f..bc2b4a6 100644 --- a/generator/states.c +++ b/generator/states.c @@ -156,6 +156,7 @@ void abort_commands (struct nbd_handle *h, assert (nbd_get_error ()); abort_commands (h, &h->cmds_to_issue); abort_commands (h, &h->cmds_in_flight); + h->in_flight = 0; if (h->sock) { h->sock->ops->close (h->sock); h->sock = NULL; @@ -165,6 +166,7 @@ void abort_commands (struct nbd_handle *h, CLOSED: abort_commands (h, &h->cmds_to_issue); abort_commands (h, &h->cmds_in_flight); + h->in_flight = 0; if (h->sock) { h->sock->ops->close (h->sock); h->sock = NULL; diff --git a/lib/aio.c b/lib/aio.c index 5df20da..2fae10d 100644 --- a/lib/aio.c +++ b/lib/aio.c @@ -85,8 +85,6 @@ nbd_unlocked_aio_command_completed (struct nbd_handle *h, prev_cmd->next = cmd->next; else h->cmds_done = cmd->next; - h->in_flight--; - assert (h->in_flight >= 0); free (cmd); diff --git a/tests/server-death.c b/tests/server-death.c index c9195c5..4093c20 100644 --- a/tests/server-death.c +++ b/tests/server-death.c @@ -128,6 +128,11 @@ main (int argc, char *argv[]) } /* Detection of the dead server completes all remaining in-flight commands */ + if (nbd_aio_in_flight (nbd) != 0) { + fprintf (stderr, "%s: test failed: nbd_aio_in_flight\n", + argv[0]); + goto fail; + } if (nbd_aio_peek_command_completed (nbd) != cookie) { fprintf (stderr, "%s: test failed: nbd_aio_peek_command_completed\n", argv[0]); @@ -148,11 +153,6 @@ main (int argc, char *argv[]) } /* With all commands retired, no further command should be pending */ - if (nbd_aio_in_flight (nbd) != 0) { - fprintf (stderr, "%s: test failed: nbd_aio_in_flight\n", - argv[0]); - goto fail; - } if (nbd_aio_peek_command_completed (nbd) != -1) { fprintf (stderr, "%s: test failed: nbd_aio_peek_command_completed\n", argv[0]); -- 2.20.1