Date: Tue, 13 Nov 2018 22:58:38 +0000 (UTC) From: Gleb Smirnoff <glebius@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r340413 - in head/sys: kern net sys Message-ID: <201811132258.wADMwctL063533@repo.freebsd.org>
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Author: glebius Date: Tue Nov 13 22:58:38 2018 New Revision: 340413 URL: https://svnweb.freebsd.org/changeset/base/340413 Log: For compatibility KPI functions like if_addr_rlock() that used to have mutexes but now are converted to epoch(9) use thread-private epoch_tracker. Embedding tracker into ifnet(9) or ifnet derived structures creates a non reentrable function, that will fail miserably if called simultaneously from two different contexts. A thread private tracker will provide a single tracker that would allow to call these functions safely. It doesn't allow nested call, but this is not expected from compatibility KPIs. Reviewed by: markj Modified: head/sys/kern/kern_thread.c head/sys/kern/subr_epoch.c head/sys/net/if.c head/sys/net/if_var.h head/sys/sys/epoch.h head/sys/sys/proc.h Modified: head/sys/kern/kern_thread.c ============================================================================== --- head/sys/kern/kern_thread.c Tue Nov 13 22:41:20 2018 (r340412) +++ head/sys/kern/kern_thread.c Tue Nov 13 22:58:38 2018 (r340413) @@ -272,6 +272,7 @@ thread_init(void *mem, int size, int flags) td->td_rlqe = NULL; EVENTHANDLER_DIRECT_INVOKE(thread_init, td); umtx_thread_init(td); + epoch_thread_init(td); td->td_kstack = 0; td->td_sel = NULL; return (0); @@ -291,6 +292,7 @@ thread_fini(void *mem, int size) turnstile_free(td->td_turnstile); sleepq_free(td->td_sleepqueue); umtx_thread_fini(td); + epoch_thread_fini(td); seltdfini(td); } Modified: head/sys/kern/subr_epoch.c ============================================================================== --- head/sys/kern/subr_epoch.c Tue Nov 13 22:41:20 2018 (r340412) +++ head/sys/kern/subr_epoch.c Tue Nov 13 22:58:38 2018 (r340413) @@ -667,3 +667,17 @@ in_epoch(epoch_t epoch) { return (in_epoch_verbose(epoch, 0)); } + +void +epoch_thread_init(struct thread *td) +{ + + td->td_et = malloc(sizeof(struct epoch_tracker), M_EPOCH, M_WAITOK); +} + +void +epoch_thread_fini(struct thread *td) +{ + + free(td->td_et, M_EPOCH); +} Modified: head/sys/net/if.c ============================================================================== --- head/sys/net/if.c Tue Nov 13 22:41:20 2018 (r340412) +++ head/sys/net/if.c Tue Nov 13 22:58:38 2018 (r340413) @@ -1767,35 +1767,29 @@ if_data_copy(struct ifnet *ifp, struct if_data *ifd) void if_addr_rlock(struct ifnet *ifp) { - MPASS(*(uint64_t *)&ifp->if_addr_et == 0); - epoch_enter_preempt(net_epoch_preempt, &ifp->if_addr_et); + + epoch_enter_preempt(net_epoch_preempt, curthread->td_et); } void if_addr_runlock(struct ifnet *ifp) { - epoch_exit_preempt(net_epoch_preempt, &ifp->if_addr_et); -#ifdef INVARIANTS - bzero(&ifp->if_addr_et, sizeof(struct epoch_tracker)); -#endif + + epoch_exit_preempt(net_epoch_preempt, curthread->td_et); } void if_maddr_rlock(if_t ifp) { - MPASS(*(uint64_t *)&ifp->if_maddr_et == 0); - epoch_enter_preempt(net_epoch_preempt, &ifp->if_maddr_et); + epoch_enter_preempt(net_epoch_preempt, curthread->td_et); } void if_maddr_runlock(if_t ifp) { - epoch_exit_preempt(net_epoch_preempt, &ifp->if_maddr_et); -#ifdef INVARIANTS - bzero(&ifp->if_maddr_et, sizeof(struct epoch_tracker)); -#endif + epoch_exit_preempt(net_epoch_preempt, curthread->td_et); } /* Modified: head/sys/net/if_var.h ============================================================================== --- head/sys/net/if_var.h Tue Nov 13 22:41:20 2018 (r340412) +++ head/sys/net/if_var.h Tue Nov 13 22:58:38 2018 (r340413) @@ -381,8 +381,6 @@ struct ifnet { */ struct netdump_methods *if_netdump_methods; struct epoch_context if_epoch_ctx; - struct epoch_tracker if_addr_et; - struct epoch_tracker if_maddr_et; /* * Spare fields to be added before branching a stable branch, so Modified: head/sys/sys/epoch.h ============================================================================== --- head/sys/sys/epoch.h Tue Nov 13 22:41:20 2018 (r340412) +++ head/sys/sys/epoch.h Tue Nov 13 22:58:38 2018 (r340413) @@ -82,5 +82,8 @@ void epoch_exit_preempt(epoch_t epoch, epoch_tracker_t void epoch_enter(epoch_t epoch); void epoch_exit(epoch_t epoch); +void epoch_thread_init(struct thread *); +void epoch_thread_fini(struct thread *); + #endif /* _KERNEL */ #endif /* _SYS_EPOCH_H_ */ Modified: head/sys/sys/proc.h ============================================================================== --- head/sys/sys/proc.h Tue Nov 13 22:41:20 2018 (r340412) +++ head/sys/sys/proc.h Tue Nov 13 22:58:38 2018 (r340413) @@ -193,6 +193,7 @@ struct trapframe; struct turnstile; struct vm_map; struct vm_map_entry; +struct epoch_tracker; /* * XXX: Does this belong in resource.h or resourcevar.h instead? @@ -360,6 +361,7 @@ struct thread { int td_lastcpu; /* (t) Last cpu we were on. */ int td_oncpu; /* (t) Which cpu we are on. */ void *td_lkpi_task; /* LinuxKPI task struct pointer */ + struct epoch_tracker *td_et; /* (k) compat KPI spare tracker */ int td_pmcpend; };
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