Date: Wed, 11 Feb 2026 05:17:38 +0000 From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 68feaa1cf268 - stable/15 - SCHED_4BSD: maybe_resched() cannot schedule ast() for curthread Message-ID: <698c10f2.2670f.34166c50@gitrepo.freebsd.org>
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The branch stable/15 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=68feaa1cf2684c520829fb245bd4b9381e655c18 commit 68feaa1cf2684c520829fb245bd4b9381e655c18 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2026-01-29 08:09:00 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2026-02-11 05:12:38 +0000 SCHED_4BSD: maybe_resched() cannot schedule ast() for curthread (cherry picked from commit b249cb2b18b3fddae186d45fe6d984fc7bde10c4) --- sys/kern/kern_synch.c | 2 +- sys/kern/sched_4bsd.c | 21 +++++++++++++++++++-- sys/sys/proc.h | 1 + sys/sys/sched.h | 2 ++ 4 files changed, 23 insertions(+), 3 deletions(-) diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c index 0ab0ccb3d05b..22628c78d8a5 100644 --- a/sys/kern/kern_synch.c +++ b/sys/kern/kern_synch.c @@ -596,7 +596,7 @@ loadav(void *arg) loadav, NULL, C_DIRECT_EXEC | C_PREL(32)); } -static void +void ast_scheduler(struct thread *td, int tda __unused) { #ifdef KTRACE diff --git a/sys/kern/sched_4bsd.c b/sys/kern/sched_4bsd.c index 317b47da2cca..a47fe3ce72c3 100644 --- a/sys/kern/sched_4bsd.c +++ b/sys/kern/sched_4bsd.c @@ -108,6 +108,8 @@ struct td_sched { #define TDF_BOUND TDF_SCHED1 /* Bound to one CPU. */ #define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */ +#define TDP_RESCHED TDP_SCHED1 /* Reschedule due to maybe_resched(). */ + /* flags kept in ts_flags */ #define TSF_AFFINITY 0x0001 /* Has a non-"full" CPU set. */ @@ -274,6 +276,17 @@ sched_load_rem(void) KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt); SDT_PROBE2(sched, , , load__change, NOCPU, sched_tdcnt); } + +static void +maybe_resched_ast(struct thread *td, int tda) +{ + MPASS(td == curthread); /* We are AST */ + if ((td->td_pflags & TDP_RESCHED) != 0) { + td->td_pflags &= ~TDP_RESCHED; + ast_scheduler(td, tda); + } +} + /* * Arrange to reschedule if necessary, taking the priorities and * schedulers into account. @@ -281,10 +294,12 @@ sched_load_rem(void) static void maybe_resched(struct thread *td) { + struct thread *ctd; + ctd = curthread; THREAD_LOCK_ASSERT(td, MA_OWNED); - if (td->td_priority < curthread->td_priority) - ast_sched_locked(curthread, TDA_SCHED); + if (td->td_priority < ctd->td_priority) + ctd->td_pflags |= TDP_RESCHED; } /* @@ -621,6 +636,8 @@ sched_4bsd_setup(void) /* Account for thread0. */ sched_load_add(); + + ast_register(TDA_SCHED_PRIV, ASTR_UNCOND, 0, maybe_resched_ast); } /* diff --git a/sys/sys/proc.h b/sys/sys/proc.h index 0c9658fff725..7c4431ab0819 100644 --- a/sys/sys/proc.h +++ b/sys/sys/proc.h @@ -503,6 +503,7 @@ enum { TDA_SIGSUSPEND, TDA_MOD3, /* .. and after */ TDA_MOD4, + TDA_SCHED_PRIV, TDA_MAX, }; #define TDAI(tda) (1U << (tda)) diff --git a/sys/sys/sched.h b/sys/sys/sched.h index 08d8636aaa68..c7b7b849947c 100644 --- a/sys/sys/sched.h +++ b/sys/sys/sched.h @@ -188,6 +188,8 @@ sched_unpin(void) curthread->td_pinned--; } +void ast_scheduler(struct thread *td, int tda); + /* sched_add arguments (formerly setrunqueue) */ #define SRQ_BORING 0x0000 /* No special circumstances. */ #define SRQ_YIELDING 0x0001 /* We are yielding (from mi_switch). */home | help
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