search for: nbd_set_debug

On Sat, Jul 15, 2023 at 08:49:51PM -0500, Eric Blake wrote: > A compliant server should not send NBD_REPLY_TYPE_BLOCK_STATUS unless > we successfully negotiated a meta context. And our default strictness > settings refuse to let us send NBD_CMD_BLOCK_STATUS unless we > negotiated a meta context. But when you mix non-default settings > (using nbd_set_strict to disable

Rich recently patched things to generate one man page per function rather than libnbd-api.3 (nice), but in doing so got stumped by a problem with a fresh git clone (automake fails for any 'include' directive that does not already exist). I've figured out how to hack around it, but the hack requires GNU make. We already use GNU make constructs elsewhere (such as $(wildcard)), but

...he GNU -# Lesser General Public License for more details. -# -# You should have received a copy of the GNU Lesser General Public -# License along with this library; if not, write to the Free Software -# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA - -api_built += \ - nbd_set_debug \ - nbd_get_debug \ - nbd_set_debug_callback \ - nbd_clear_debug_callback \ - nbd_set_handle_name \ - nbd_get_handle_name \ - nbd_set_export_name \ - nbd_get_export_name \ - nbd_set_tls \ - nbd_get_tls \ - nbd_set_tls_certificates \ - nbd_set_tls_verify_peer \ - nbd_get_tls_verify_peer \ - nbd_set_...

...the GNU +# Lesser General Public License for more details. +# +# You should have received a copy of the GNU Lesser General Public +# License along with this library; if not, write to the Free Software +# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + +api_built = \ + nbd_set_debug \ + nbd_get_debug \ + nbd_set_debug_callback \ + nbd_clear_debug_callback \ + nbd_set_handle_name \ + nbd_get_handle_name \ + nbd_set_export_name \ + nbd_get_export_name \ + nbd_set_tls \ + nbd_get_tls \ + nbd_set_tls_certificates \ + nbd_set_tls_verify_peer \ + nbd_get_tls_verify_peer \ + nbd_set_...

...*arg) +{ + struct pollfd fds[1]; + struct nbd_connection *conn; + char buf[512]; + size_t i, j; + int64_t handles[2]; + size_t in_flight; /* counts number of requests in flight */ + int dir, r, cmd; + bool want_to_send; + + /* The single thread "owns" the connection. */ + nbd_set_debug (nbd, true); + conn = nbd_get_connection (nbd, 0); + + /* Issue commands. */ + in_flight = 0; + fprintf (stderr, " * before aio_pread\n"); + handles[0] = nbd_aio_pread (conn, in, packetsize, 0); + if (handles[0] == -1) { + fprintf (stderr, "%s\n", nbd_get_error ()); +...

For example nbd_set_debug takes a callback function. Previously this was defined explicitly inside the function parameters. This commit defines a new public typedef: typedef int (*nbd_debug_callback) (unsigned valid_flag, void *user_data, const char *context, const char *msg); and...

This might not be the final solution, but it certainly seems to solve a deadlock for me that I could trigger by using 'nbdkit --filter=noparallel memory 512k' and calling nbd_aio_pread for a request larger than 256k (enough for the Linux kernel to block the server until libnbd read()s), immediately followed by nbd_aio_pwrite for a request larger than 256k (enough to block libnbd until the

...) > +{ > + struct nbd_handle *nbd; > + int64_t cookie; > + char buf[512]; > + > + /* Check debug functions are freed when a new debug function is > + * registered, and when the handle is closed. > + */ > + nbd = nbd_create (); > + assert (nbd); > + > + nbd_set_debug_callback (nbd, debug_fn, NULL); > + assert (debug_fn_free == 0); > + > + nbd_set_debug_callback (nbd, debug_fn, NULL); > + assert (debug_fn_free == 1); If you add asserts against use-after-free above, you'd also need to reset debug_fn_free back to 0 here. > + > + nbd_clo...

I think I've addressed everything that was raised in review. Some of the highlights: - Callbacks should be freed reliably along all exit paths. - There's a simple test of closure lifetimes. - I've tried to use VALID|FREE in all the places where I'm confident that it's safe and correct to do. There may be more places. Note this is an optimization and shouldn't