search for: nbd_aio_is_

...tified by Eric Blake: > > Thread A Thread B > (in a call that holds h->lock) (calling nbd_aio_pread) > -------------------------------------------------------------------- > h->state is processing > checks nbd_aio_is_ready > (it's false) > h->state is moved to READY > checks nbd_aio_is_processing > (it's false) > validation check fails > &...

On 6/5/19 6:15 AM, Richard W.M. Jones wrote: > Simple code motion. > --- > lib/Makefile.am | 1 + > lib/aio.c | 78 ----------------------------------- > lib/is-state.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 106 insertions(+), 78 deletions(-) > > +++ b/lib/is-state.c > @@ -0,0 +1,105 @@ > +#include <config.h>

Simple code motion. --- lib/Makefile.am | 1 + lib/aio.c | 78 ----------------------------------- lib/is-state.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 106 insertions(+), 78 deletions(-) diff --git a/lib/Makefile.am b/lib/Makefile.am index 312545e..72d2d0b 100644 --- a/lib/Makefile.am +++ b/lib/Makefile.am @@ -42,6 +42,7 @@ libnbd_la_SOURCES = \

...is fixes a race condition identified by Eric Blake: Thread A Thread B (in a call that holds h->lock) (calling nbd_aio_pread) -------------------------------------------------------------------- h->state is processing checks nbd_aio_is_ready (it's false) h->state is moved to READY checks nbd_aio_is_processing (it's false) validation check fails (However the state was valid so...

This works. I'm in the middle of testing whether there is any noticable benefit. Rich.

...ere the user reads the public state while another thread holds the lock, their future actions based on the observed state may be unexpected by the time they actually grab the lock because the other thread changed state), as well as the issue I mentioned in on 3/4 about any consecutive user calls to nbd_aio_is_* having a race where the two calls can be done on different public states. I'm still thinking that for any functions that grab the lock but want to do gating on state MUST save the public state check until after grabbing the lock, not beforehand, to avoid the TOCTTOU race. > --- > gene...

I need to think about this patch series a bit more, but it does at least pass the tests. Rich.