On Tue, Jan 28, 2020 at 04:58:00PM +0100, Corentin Labbe wrote: > On Tue, Jan 28, 2020 at 03:50:14PM +0000, Horia Geanta wrote: > > On 1/22/2020 12:46 PM, Corentin Labbe wrote: > > > Some bykeshedding are unnecessary since a workqueue can only be executed > > > one by one. > > > This behaviour is documented in: > > > - kernel/kthread.c: comment of kthread_worker_fn() > > > - Documentation/core-api/workqueue.rst: the functions associated with the work items one after the other > > [...] > > > @@ -73,16 +73,6 @@ static void crypto_pump_requests(struct crypto_engine *engine, > > > > > > spin_lock_irqsave(&engine->queue_lock, flags); > > > > > > - /* Make sure we are not already running a request */ > > > - if (engine->cur_req) > > > - goto out; > > > - > > This check is here for a good reason, namely because crypto engine > > cannot currently handle multiple crypto requests being in "flight" > > in parallel. > > > > More exactly, if this check is removed the following sequence could occur: > > crypto_pump_work() -> crypto_pump_requests() -> .do_one_request(areq1) > > crypto_pump_work() -> crypto_pump_requests() -> .do_one_request(areq2) > > crypto_finalize_request(areq1) > > crypto_finalize_request(areq2) > > > > As explained in the commitlog, crypto_pump_work() cannot be ran twice. > Sorry, I have misunderstood and wrongly answered. Right since some driver does not block on do_one_request(), crypto_pump_work() can be ran one after one and so launch two request. So this patch is bad. Regards
