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Apply r355819 to sparc64 - fix assertion failure after r355784

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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
This commit is contained in:
emaste 2020-01-23 14:11:02 +00:00
parent 1726ab2174
commit 3f2a276c5a
1 changed files with 4 additions and 3 deletions
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7
sys/sparc64/sparc64/machdep.c
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@ -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