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| author | Daniel Thompson <daniel.thompson@linaro.org> | 2020-05-06 17:42:23 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-06-22 09:05:15 +0200 |
| commit | 875e941843112c141f48cb4d1e20b2a4d312c143 (patch) | |
| tree | d3e68f8b9a21c2284de4ed542447d2782da340b2 /include | |
| parent | d31ac33174303418dbe533deafdf2333abd0c693 (diff) | |
| download | linux-875e941843112c141f48cb4d1e20b2a4d312c143.tar.gz linux-875e941843112c141f48cb4d1e20b2a4d312c143.tar.bz2 linux-875e941843112c141f48cb4d1e20b2a4d312c143.zip | |
kgdb: Fix spurious true from in_dbg_master()
[ Upstream commit 3fec4aecb311995189217e64d725cfe84a568de3 ]
Currently there is a small window where a badly timed migration could
cause in_dbg_master() to spuriously return true. Specifically if we
migrate to a new core after reading the processor id and the previous
core takes a breakpoint then we will evaluate true if we read
kgdb_active before we get the IPI to bring us to halt.
Fix this by checking irqs_disabled() first. Interrupts are always
disabled when we are executing the kgdb trap so this is an acceptable
prerequisite. This also allows us to replace raw_smp_processor_id()
with smp_processor_id() since the short circuit logic will prevent
warnings from PREEMPT_DEBUG.
Fixes: dcc7871128e9 ("kgdb: core changes to support kdb")
Suggested-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200506164223.2875760-1-daniel.thompson@linaro.org
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/kgdb.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index e465bb15912d..6be5545d3584 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -317,7 +317,7 @@ extern void gdbstub_exit(int status); extern int kgdb_single_step; extern atomic_t kgdb_active; #define in_dbg_master() \ - (raw_smp_processor_id() == atomic_read(&kgdb_active)) + (irqs_disabled() && (smp_processor_id() == atomic_read(&kgdb_active))) extern bool dbg_is_early; extern void __init dbg_late_init(void); #else /* ! CONFIG_KGDB */ |