Date: Fri, 31 Jan 2020 08:36:49 +0000 (UTC) From: Mateusz Guzik <mjg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r357320 - in head/sys: kern sys Message-ID: <202001310836.00V8anjE057688@repo.freebsd.org>
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Author: mjg Date: Fri Jan 31 08:36:49 2020 New Revision: 357320 URL: https://svnweb.freebsd.org/changeset/base/357320 Log: Add rms_try_rlock and rms_wowned. Modified: head/sys/kern/kern_rmlock.c head/sys/sys/rmlock.h Modified: head/sys/kern/kern_rmlock.c ============================================================================== --- head/sys/kern/kern_rmlock.c Fri Jan 31 08:36:23 2020 (r357319) +++ head/sys/kern/kern_rmlock.c Fri Jan 31 08:36:49 2020 (r357320) @@ -934,6 +934,30 @@ rms_rlock(struct rmslock *rms) critical_exit(); } +int +rms_try_rlock(struct rmslock *rms) +{ + int *influx; + + critical_enter(); + influx = zpcpu_get(rms->readers_influx); + __compiler_membar(); + *influx = 1; + __compiler_membar(); + if (__predict_false(rms->writers > 0)) { + __compiler_membar(); + *influx = 0; + critical_exit(); + return (0); + } + __compiler_membar(); + (*zpcpu_get(rms->readers_pcpu))++; + __compiler_membar(); + *influx = 0; + critical_exit(); + return (1); +} + static void __noinline rms_runlock_fallback(struct rmslock *rms) { Modified: head/sys/sys/rmlock.h ============================================================================== --- head/sys/sys/rmlock.h Fri Jan 31 08:36:23 2020 (r357319) +++ head/sys/sys/rmlock.h Fri Jan 31 08:36:49 2020 (r357320) @@ -136,9 +136,21 @@ struct rm_args { void rms_init(struct rmslock *rms, const char *name); void rms_destroy(struct rmslock *rms); void rms_rlock(struct rmslock *rms); +int rms_try_rlock(struct rmslock *rms); void rms_runlock(struct rmslock *rms); void rms_wlock(struct rmslock *rms); void rms_wunlock(struct rmslock *rms); + +/* + * Writers are not explicitly tracked, thus until that changes the best we can + * do is indicate the lock is taken for writing by *someone*. + */ +static inline int +rms_wowned(struct rmslock *rms) +{ + + return (rms->writers > 0); +} #endif /* _KERNEL */ #endif /* !_SYS_RMLOCK_H_ */
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