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CVS commit: src/sys/arch/sparc/sparc

Module Name:    src
Committed By:   mrg
Date:           Thu Jan 27 05:31:14 UTC 2011

Modified Files:
        src/sys/arch/sparc/sparc: cpu.c cpuvar.h intr.c

Log Message:
to quote a new comment:

 * There's a deadlock potential between multiple CPUs trying
 * to xcall() at the same time, and the thread that loses the
 * race to get xpmsg_lock is at an IPL above the incoming IPI
 * IPL level, so it sits around waiting to take the lock while
 * the other CPU is waiting for this CPU to handle the IPI and
 * mark it as completed.
 * If we fail to get the mutex, and we're at high enough IPL,
 * call xcallintr() if there is a valid msg.tag.

this seems to fix the xcall() failed to ping cpus problem.
idea from martin, tested by macallan and myself.

To generate a diff of this commit:
cvs rdiff -u -r1.225 -r1.226 src/sys/arch/sparc/sparc/cpu.c
cvs rdiff -u -r1.84 -r1.85 src/sys/arch/sparc/sparc/cpuvar.h
cvs rdiff -u -r1.109 -r1.110 src/sys/arch/sparc/sparc/intr.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

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