| Message ID | 172196639503.18529.16126598330625338469@noble.neil.brown.name (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | sunrpc: document locking rules for svc_exit_thread() | expand |
On Fri, 2024-07-26 at 13:59 +1000, NeilBrown wrote: > > The locking required for svc_exit_thread() is not obvious, so document > it in a kdoc comment. > > Signed-off-by: NeilBrown <neilb@suse.de> > --- > > Rather than repost patch 5/14 of my recent set for dynamic thread > management, I decided to provide this as an independent patch which > could usefully be inserted into the series before 5/14. That will make > that patch easier to understand/review. > > NeilBrown > > > net/sunrpc/svc.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c > index 26b6e73fc0de..4c3df893c532 100644 > --- a/net/sunrpc/svc.c > +++ b/net/sunrpc/svc.c > @@ -955,6 +955,20 @@ void svc_rqst_release_pages(struct svc_rqst *rqstp) > } > } > > +/** > + * svc_exit_thread - finalise the termination of a sunrpc server thread > + * @rqstp: the svc_rqst which represents the thread. > + * > + * When a thread started with svc_new_thread() exits it must call > + * svc_exit_thread() as its last act. This must be done with the > + * service mutex held. Normally this is held by a DIFFERENT thread, the > + * one that is calling svc_set_num_threads() and which will wait for > + * SP_VICTIM_REMAINS to be cleared before dropping the mutex. If the > + * thread exits for any reason other than svc_thread_should_stop() > + * returning %true (which indicated that svc_set_num_threads() is > + * waiting for it to exit), then it must take the service mutex itself, > + * which can only safely be done using mutex_try_lock(). > + */ > void > svc_exit_thread(struct svc_rqst *rqstp) > { Nice to have this clearly stated. Reviewed-by: Jeff Layton <jlayton@kernel.org>
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 26b6e73fc0de..4c3df893c532 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -955,6 +955,20 @@ void svc_rqst_release_pages(struct svc_rqst *rqstp) } } +/** + * svc_exit_thread - finalise the termination of a sunrpc server thread + * @rqstp: the svc_rqst which represents the thread. + * + * When a thread started with svc_new_thread() exits it must call + * svc_exit_thread() as its last act. This must be done with the + * service mutex held. Normally this is held by a DIFFERENT thread, the + * one that is calling svc_set_num_threads() and which will wait for + * SP_VICTIM_REMAINS to be cleared before dropping the mutex. If the + * thread exits for any reason other than svc_thread_should_stop() + * returning %true (which indicated that svc_set_num_threads() is + * waiting for it to exit), then it must take the service mutex itself, + * which can only safely be done using mutex_try_lock(). + */ void svc_exit_thread(struct svc_rqst *rqstp) {
The locking required for svc_exit_thread() is not obvious, so document it in a kdoc comment. Signed-off-by: NeilBrown <neilb@suse.de> --- Rather than repost patch 5/14 of my recent set for dynamic thread management, I decided to provide this as an independent patch which could usefully be inserted into the series before 5/14. That will make that patch easier to understand/review. NeilBrown net/sunrpc/svc.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)