Date: Wed, 23 Jan 2013 22:52:20 +0000 (UTC) From: Marius Strobl <marius@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r245850 - in head/sys/sparc64: include sparc64 Message-ID: <201301232252.r0NMqLxh085107@svn.freebsd.org>
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Author: marius Date: Wed Jan 23 22:52:20 2013 New Revision: 245850 URL: http://svnweb.freebsd.org/changeset/base/245850 Log: Revert the part of r239864 which removed obtaining the SMP mutex around reading registers from other CPUs. As it turns out, the hardware doesn't really like concurrent IPI'ing causing adverse effects. Also the thought deadlock when using this spin lock here and the targeted CPU(s) are also holding or in case of nested locks can't actually happen. This is due to the fact that on sparc64, spinlock_enter() only raises the PIL but doesn't disable interrupts completely. Thus direct cross calls as used for the register reading (and all other MD IPI needs) still will be executed by the targeted CPU(s) in that case. MFC after: 3 days Modified: head/sys/sparc64/include/smp.h head/sys/sparc64/sparc64/tick.c Modified: head/sys/sparc64/include/smp.h ============================================================================== --- head/sys/sparc64/include/smp.h Wed Jan 23 21:44:48 2013 (r245849) +++ head/sys/sparc64/include/smp.h Wed Jan 23 22:52:20 2013 (r245850) @@ -42,6 +42,7 @@ #include <sys/cpuset.h> #include <sys/proc.h> #include <sys/sched.h> +#include <sys/smp.h> #include <machine/intr_machdep.h> #include <machine/pcb.h> @@ -202,6 +203,7 @@ ipi_rd(u_int cpu, void *func, u_long *va return (NULL); sched_pin(); ira = &ipi_rd_args; + mtx_lock_spin(&smp_ipi_mtx); CPU_SETOF(cpu, &ira->ira_mask); ira->ira_val = val; cpu_ipi_single(cpu, 0, (u_long)func, (u_long)ira); @@ -298,18 +300,6 @@ ipi_wait(void *cookie) } } -static __inline void -ipi_wait_unlocked(void *cookie) -{ - volatile cpuset_t *mask; - - if ((mask = cookie) != NULL) { - while (!CPU_EMPTY(mask)) - ; - sched_unpin(); - } -} - #endif /* _MACHINE_PMAP_H_ && _SYS_MUTEX_H_ */ #endif /* !LOCORE */ @@ -368,12 +358,6 @@ ipi_wait(void *cookie __unused) } static __inline void -ipi_wait_unlocked(void *cookie __unused) -{ - -} - -static __inline void tl_ipi_cheetah_dcache_page_inval(void) { Modified: head/sys/sparc64/sparc64/tick.c ============================================================================== --- head/sys/sparc64/sparc64/tick.c Wed Jan 23 21:44:48 2013 (r245849) +++ head/sys/sparc64/sparc64/tick.c Wed Jan 23 22:52:20 2013 (r245850) @@ -334,7 +334,7 @@ stick_get_timecount_mp(struct timecounte if (curcpu == 0) stick = rdstick(); else - ipi_wait_unlocked(ipi_rd(0, tl_ipi_stick_rd, &stick)); + ipi_wait(ipi_rd(0, tl_ipi_stick_rd, &stick)); sched_unpin(); return (stick); } @@ -348,7 +348,7 @@ tick_get_timecount_mp(struct timecounter if (curcpu == 0) tick = rd(tick); else - ipi_wait_unlocked(ipi_rd(0, tl_ipi_tick_rd, &tick)); + ipi_wait(ipi_rd(0, tl_ipi_tick_rd, &tick)); sched_unpin(); return (tick); }
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