Date: Thu, 23 Jan 2020 14:11:02 +0000 (UTC) From: Ed Maste <emaste@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r357045 - head/sys/sparc64/sparc64 Message-ID: <202001231411.00NEB2FA090930@repo.freebsd.org>
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Author: emaste Date: Thu Jan 23 14:11:02 2020 New Revision: 357045 URL: https://svnweb.freebsd.org/changeset/base/357045 Log: Apply r355819 to sparc64 - fix assertion failure after r355784 From r355819: Repeat the spinlock_enter/exit pattern from amd64 on other architectures to fix an assert violation introduced in r355784. Without this spinlock_exit() may see owepreempt and switch before reducing the spinlock count. amd64 had been optimized to do a single critical enter/exit regardless of the number of spinlocks which avoided the problem and this optimization had not been applied elsewhere. This is completely untested - I have no obsolete Sparc hardware - but someone did try testing recent changes on sparc64 (PR 243534). PR: 243534 Modified: head/sys/sparc64/sparc64/machdep.c Modified: head/sys/sparc64/sparc64/machdep.c ============================================================================== --- head/sys/sparc64/sparc64/machdep.c Thu Jan 23 14:01:03 2020 (r357044) +++ head/sys/sparc64/sparc64/machdep.c Thu Jan 23 14:11:02 2020 (r357045) @@ -224,9 +224,9 @@ spinlock_enter(void) wrpr(pil, 0, PIL_TICK); td->td_md.md_spinlock_count = 1; td->td_md.md_saved_pil = pil; + critical_enter(); } else td->td_md.md_spinlock_count++; - critical_enter(); } void @@ -236,11 +236,12 @@ spinlock_exit(void) register_t pil; td = curthread; - critical_exit(); pil = td->td_md.md_saved_pil; td->td_md.md_spinlock_count--; - if (td->td_md.md_spinlock_count == 0) + if (td->td_md.md_spinlock_count == 0) { + critical_exit(); wrpr(pil, pil, 0); + } } static phandle_t
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