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| author | Andy Lutomirski <luto@kernel.org> | 2020-12-03 21:07:03 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-12-16 10:56:59 +0100 |
| commit | e3c1d51868f33ea4979ec8f61fc183a5ebfa8a7a (patch) | |
| tree | 639d8e36255d5a6859c05c1ffcbe95724d4d7ad9 /arch/x86/kernel/apic/vector.c | |
| parent | 6346ed69bc7c84161c07875bf3e0f5523b4bca8d (diff) | |
x86/membarrier: Get rid of a dubious optimization
commit a493d1ca1a03b532871f1da27f8dbda2b28b04c4 upstream.
sync_core_before_usermode() had an incorrect optimization. If the kernel
returns from an interrupt, it can get to usermode without IRET. It just has
to schedule to a different task in the same mm and do SYSRET. Fortunately,
there were no callers of sync_core_before_usermode() that could have had
in_irq() or in_nmi() equal to true, because it's only ever called from the
scheduler.
While at it, clarify a related comment.
Fixes: 70216e18e519 ("membarrier: Provide core serializing command, *_SYNC_CORE")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/5afc7632be1422f91eaf7611aaaa1b5b8580a086.1607058304.git.luto@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/kernel/apic/vector.c')
0 files changed, 0 insertions, 0 deletions