Date: Fri, 13 Nov 2015 16:41:44 -0500 From: Randall Stewart <rrs@netflix.com> To: "Alexander V. Chernikov" <melifaro@ipfw.ru> Cc: "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, Adrian Chadd <adrian@freebsd.org>, "imp@freebsd.org" <imp@freebsd.org> Subject: Re: svn commit: r290664 - in head: share/man/man9 sys/kern sys/sys Message-ID: <19FCC2F9-0986-4106-9559-75E65184704C@netflix.com> In-Reply-To: <81431447450321@web13o.yandex.ru> References: null <201511101449.tAAEnXIi065747@repo.freebsd.org> <1660421447413365@web19h.yandex.ru> <758BC83D-E327-4B08-9103-C31EC4DDB193@netflix.com> <81431447450321@web13o.yandex.ru>
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Hmm callout_reset() returns either 0 or 1=20 It returns no other values and did not change.. maybe ti should say = positive or one in the manual=85 I can add that to the fix patch. R On Nov 13, 2015, at 4:32 PM, Alexander V. Chernikov <melifaro@ipfw.ru> = wrote: > One small note on lltable: change in nd6_llinfo_settimer_locked() = assumes that callout_reset() returns >0 for stopped callout. The man = page still says "non-zero value" for that case. > (And that was the reason of writing comment to D4076 on inconsistent = callout_reset() return value). > =20 >=20 >=20 > 14.11.2015, 00:19, "Randall Stewart" <rrs@netflix.com>: >> So looking deeper something like the following (with Bryan=92s patch) = is in order. >>=20 >> Though there is one place in the task code that looks funny since it = was >>=20 >> pending =3D !!callout_stop() >>=20 >> I changed it to >>=20 >> pending =3D !! (callout_stop > 0) >>=20 >> But I wonder about the double !! that seems rather convoluted.. >>=20 >> Unless someone objects I will commit this shortly >> R >>=20 >>=20 >>=20 >> , >> On Nov 13, 2015, at 6:16 AM, Alexander V. Chernikov = <melifaro@freebsd.org> wrote: >>=20 >>> 10.11.2015, 17:49, "Randall Stewart" <rrs@FreeBSD.org>: >>>> Author: rrs >>>> Date: Tue Nov 10 14:49:32 2015 >>>> New Revision: 290664 >>>> URL: https://svnweb.freebsd.org/changeset/base/290664 >>>>=20 >>>> Log: >>>> Add new async_drain to the callout system. This is so-far not = used but >>>> should be used by TCP for sure in its cleanup of the IN-PCB (will = be coming shortly). >>>=20 >>> Randall, this commit introduced change in callout_stop() which was = not mentioned in commit message. >>> This change has broken lltable arp/nd handling: deleting interface = address causes immediate panic. >>> I also see other other code/subsystems relying on callout_stop() = return value (netgraph, pfsync, iscsi). >>> I was not able to find any discussion/analysis/testing for these in = D4076 so this change does not look like being properly tested prior = commiting.. >>>=20 >>>=20 >>>>=20 >>>> Sponsored by: Netflix Inc. >>>> Differential Revision: https://reviews.freebsd.org/D4076 >>>>=20 >>>> Modified: >>>> head/share/man/man9/timeout.9 >>>> head/sys/kern/kern_timeout.c >>>> head/sys/sys/callout.h >>>>=20 >>>> Modified: head/share/man/man9/timeout.9 >>>> = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D >>>> --- head/share/man/man9/timeout.9 Tue Nov 10 14:14:41 2015 = (r290663) >>>> +++ head/share/man/man9/timeout.9 Tue Nov 10 14:49:32 2015 = (r290664) >>>> @@ -35,6 +35,7 @@ >>>> .Sh NAME >>>> .Nm callout_active , >>>> .Nm callout_deactivate , >>>> +.Nm callout_async_drain , >>>> .Nm callout_drain , >>>> .Nm callout_handle_init , >>>> .Nm callout_init , >>>> @@ -69,6 +70,8 @@ typedef void timeout_t (void *); >>>> .Ft void >>>> .Fn callout_deactivate "struct callout *c" >>>> .Ft int >>>> +.Fn callout_async_drain "struct callout *c" "timeout_t *drain" >>>> +.Ft int >>>> .Fn callout_drain "struct callout *c" >>>> .Ft void >>>> .Fn callout_handle_init "struct callout_handle *handle" >>>> @@ -236,17 +239,42 @@ The function >>>> cancels a callout >>>> .Fa c >>>> if it is currently pending. >>>> -If the callout is pending, then >>>> +If the callout is pending and successfuly stopped, then >>>> .Fn callout_stop >>>> -returns a non-zero value. >>>> -If the callout is not set, >>>> -has already been serviced, >>>> -or is currently being serviced, >>>> +returns a value of one. >>>> +If the callout is not set, or >>>> +has already been serviced, then >>>> +negative one is returned. >>>> +If the callout is currently being serviced and cannot be stopped, >>>> then zero will be returned. >>>> If the callout has an associated lock, >>>> then that lock must be held when this function is called. >>>> .Pp >>>> The function >>>> +.Fn callout_async_drain >>>> +is identical to >>>> +.Fn callout_stop >>>> +with one difference. >>>> +When >>>> +.Fn callout_async_drain >>>> +returns zero it will arrange for the function >>>> +.Fa drain >>>> +to be called using the same argument given to the >>>> +.Fn callout_reset >>>> +function. >>>> +.Fn callout_async_drain >>>> +If the callout has an associated lock, >>>> +then that lock must be held when this function is called. >>>> +Note that when stopping multiple callouts that use the same lock = it is possible >>>> +to get multiple return's of zero and multiple calls to the >>>> +.Fa drain >>>> +function, depending upon which CPU's the callouts are running. The >>>> +.Fa drain >>>> +function itself is called from the context of the completing = callout >>>> +i.e. softclock or hardclock, just like a callout itself. >>>> +p >>>> +.Pp >>>> +The function >>>> .Fn callout_drain >>>> is identical to >>>> .Fn callout_stop >>>>=20 >>>> Modified: head/sys/kern/kern_timeout.c >>>> = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D >>>> --- head/sys/kern/kern_timeout.c Tue Nov 10 14:14:41 2015 (r290663) >>>> +++ head/sys/kern/kern_timeout.c Tue Nov 10 14:49:32 2015 (r290664) >>>> @@ -136,6 +136,7 @@ u_int callwheelsize, callwheelmask; >>>> */ >>>> struct cc_exec { >>>> struct callout *cc_curr; >>>> + void (*cc_drain)(void *); >>>> #ifdef SMP >>>> void (*ce_migration_func)(void *); >>>> void *ce_migration_arg; >>>> @@ -170,6 +171,7 @@ struct callout_cpu { >>>> #define callout_migrating(c) ((c)->c_iflags & = CALLOUT_DFRMIGRATION) >>>>=20 >>>> #define cc_exec_curr(cc, dir) cc->cc_exec_entity[dir].cc_curr >>>> +#define cc_exec_drain(cc, dir) cc->cc_exec_entity[dir].cc_drain >>>> #define cc_exec_next(cc) cc->cc_next >>>> #define cc_exec_cancel(cc, dir) cc->cc_exec_entity[dir].cc_cancel >>>> #define cc_exec_waiting(cc, dir) = cc->cc_exec_entity[dir].cc_waiting >>>> @@ -679,6 +681,7 @@ softclock_call_cc(struct callout *c, str >>>>=20 >>>> cc_exec_curr(cc, direct) =3D c; >>>> cc_exec_cancel(cc, direct) =3D false; >>>> + cc_exec_drain(cc, direct) =3D NULL; >>>> CC_UNLOCK(cc); >>>> if (c_lock !=3D NULL) { >>>> class->lc_lock(c_lock, lock_status); >>>> @@ -744,6 +747,15 @@ skip: >>>> CC_LOCK(cc); >>>> KASSERT(cc_exec_curr(cc, direct) =3D=3D c, ("mishandled = cc_curr")); >>>> cc_exec_curr(cc, direct) =3D NULL; >>>> + if (cc_exec_drain(cc, direct)) { >>>> + void (*drain)(void *); >>>> + >>>> + drain =3D cc_exec_drain(cc, direct); >>>> + cc_exec_drain(cc, direct) =3D NULL; >>>> + CC_UNLOCK(cc); >>>> + drain(c_arg); >>>> + CC_LOCK(cc); >>>> + } >>>> if (cc_exec_waiting(cc, direct)) { >>>> /* >>>> * There is someone waiting for the >>>> @@ -1145,7 +1157,7 @@ callout_schedule(struct callout *c, int >>>> } >>>>=20 >>>> int >>>> -_callout_stop_safe(struct callout *c, int safe) >>>> +_callout_stop_safe(struct callout *c, int safe, void (*drain)(void = *)) >>>> { >>>> struct callout_cpu *cc, *old_cc; >>>> struct lock_class *class; >>>> @@ -1225,19 +1237,22 @@ again: >>>> * stop it by other means however. >>>> */ >>>> if (!(c->c_iflags & CALLOUT_PENDING)) { >>>> - c->c_flags &=3D ~CALLOUT_ACTIVE; >>>> - >>>> /* >>>> * If it wasn't on the queue and it isn't the = current >>>> * callout, then we can't stop it, so just bail. >>>> + * It probably has already been run (if locking >>>> + * is properly done). You could get here if the caller >>>> + * calls stop twice in a row for example. The second >>>> + * call would fall here without CALLOUT_ACTIVE set. >>>> */ >>>> + c->c_flags &=3D ~CALLOUT_ACTIVE; >>>> if (cc_exec_curr(cc, direct) !=3D c) { >>>> CTR3(KTR_CALLOUT, "failed to stop %p func = %p arg %p", >>>> c, c->c_func, c->c_arg); >>>> CC_UNLOCK(cc); >>>> if (sq_locked) >>>> = sleepq_release(&cc_exec_waiting(cc, direct)); >>>> - return (0); >>>> + return (-1); >>>> } >>>>=20 >>>> if (safe) { >>>> @@ -1298,14 +1313,16 @@ again: >>>> CC_LOCK(cc); >>>> } >>>> } else if (use_lock && >>>> - !cc_exec_cancel(cc, direct)) { >>>> + !cc_exec_cancel(cc, direct) && (drain =3D=3D NULL)) { >>>>=20 >>>> /* >>>> * The current callout is waiting for its >>>> * lock which we hold. Cancel the callout >>>> * and return. After our caller drops the >>>> * lock, the callout will be skipped in >>>> - * softclock(). >>>> + * softclock(). This *only* works with a >>>> + * callout_stop() *not* callout_drain() or >>>> + * callout_async_drain(). >>>> */ >>>> cc_exec_cancel(cc, direct) =3D true; >>>> CTR3(KTR_CALLOUT, "cancelled %p func %p = arg %p", >>>> @@ -1351,11 +1368,17 @@ again: >>>> #endif >>>> CTR3(KTR_CALLOUT, "postponing stop %p func = %p arg %p", >>>> c, c->c_func, c->c_arg); >>>> + if (drain) { >>>> + cc_exec_drain(cc, direct) =3D drain; >>>> + } >>>> CC_UNLOCK(cc); >>>> return (0); >>>> } >>>> CTR3(KTR_CALLOUT, "failed to stop %p func %p arg = %p", >>>> c, c->c_func, c->c_arg); >>>> + if (drain) { >>>> + cc_exec_drain(cc, direct) =3D drain; >>>> + } >>>> CC_UNLOCK(cc); >>>> KASSERT(!sq_locked, ("sleepqueue chain still = locked")); >>>> return (0); >>>>=20 >>>> Modified: head/sys/sys/callout.h >>>> = =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D >>>> --- head/sys/sys/callout.h Tue Nov 10 14:14:41 2015 (r290663) >>>> +++ head/sys/sys/callout.h Tue Nov 10 14:49:32 2015 (r290664) >>>> @@ -81,7 +81,7 @@ struct callout_handle { >>>> */ >>>> #define callout_active(c) ((c)->c_flags & CALLOUT_ACTIVE) >>>> #define callout_deactivate(c) ((c)->c_flags &=3D ~CALLOUT_ACTIVE) >>>> -#define callout_drain(c) _callout_stop_safe(c, 1) >>>> +#define callout_drain(c) _callout_stop_safe(c, 1, NULL) >>>> void callout_init(struct callout *, int); >>>> void _callout_init_lock(struct callout *, struct lock_object *, = int); >>>> #define callout_init_mtx(c, mtx, flags) \ >>>> @@ -119,10 +119,11 @@ int callout_schedule(struct callout *, i >>>> int callout_schedule_on(struct callout *, int, int); >>>> #define callout_schedule_curcpu(c, on_tick) \ >>>> callout_schedule_on((c), (on_tick), PCPU_GET(cpuid)) >>>> -#define callout_stop(c) _callout_stop_safe(c, 0) >>>> -int _callout_stop_safe(struct callout *, int); >>>> +#define callout_stop(c) _callout_stop_safe(c, 0, NULL) >>>> +int _callout_stop_safe(struct callout *, int, void (*)(void *)); >>>> void callout_process(sbintime_t now); >>>> - >>>> +#define callout_async_drain(c, d) \ >>>> + _callout_stop_safe(c, 0, d) >>>> #endif >>>>=20 >>>> #endif /* _SYS_CALLOUT_H_ */ >>=20 >> -------- >> Randall Stewart >> rrs@netflix.com >> 803-317-4952 >>=20 >>=20 >>=20 >>=20 >>=20 -------- Randall Stewart rrs@netflix.com 803-317-4952
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