Searched hist:"42 f51fb2" (Results 1 – 2 of 2) sorted by relevance
| /openbmc/linux/arch/arc/include/asm/ |
| H A D | atomic-llsc.h | 42f51fb2 Tue Aug 15 10:11:36 CDT 2023 Pavel Kozlov <pavel.kozlov@synopsys.com> ARC: atomics: Add compiler barrier to atomic operations...
... to avoid unwanted gcc optimizations
SMP kernels fail to boot with commit 596ff4a09b89
("cpumask: re-introduce constant-sized cpumask optimizations").
|
| percpu: BUG: failure at mm/percpu.c:2981/pcpu_build_alloc_info()!
|
The write operation performed by the SCOND instruction in the atomic
inline asm code is not properly passed to the compiler. The compiler
cannot correctly optimize a nested loop that runs through the cpumask
in the pcpu_build_alloc_info() function.
Fix this by add a compiler barrier (memory clobber in inline asm).
Apparently atomic ops used to have memory clobber implicitly via
surrounding smp_mb(). However commit b64be6836993c431e
("ARC: atomics: implement relaxed variants") removed the smp_mb() for
the relaxed variants, but failed to add the explicit compiler barrier.
Link: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/135
Cc: <stable@vger.kernel.org> # v6.3+
Fixes: b64be6836993c43 ("ARC: atomics: implement relaxed variants")
Signed-off-by: Pavel Kozlov <pavel.kozlov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
[vgupta: tweaked the changelog and added Fixes tag]
|
| H A D | atomic64-arcv2.h | 42f51fb2 Tue Aug 15 10:11:36 CDT 2023 Pavel Kozlov <pavel.kozlov@synopsys.com> ARC: atomics: Add compiler barrier to atomic operations...
... to avoid unwanted gcc optimizations
SMP kernels fail to boot with commit 596ff4a09b89
("cpumask: re-introduce constant-sized cpumask optimizations").
|
| percpu: BUG: failure at mm/percpu.c:2981/pcpu_build_alloc_info()!
|
The write operation performed by the SCOND instruction in the atomic
inline asm code is not properly passed to the compiler. The compiler
cannot correctly optimize a nested loop that runs through the cpumask
in the pcpu_build_alloc_info() function.
Fix this by add a compiler barrier (memory clobber in inline asm).
Apparently atomic ops used to have memory clobber implicitly via
surrounding smp_mb(). However commit b64be6836993c431e
("ARC: atomics: implement relaxed variants") removed the smp_mb() for
the relaxed variants, but failed to add the explicit compiler barrier.
Link: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/135
Cc: <stable@vger.kernel.org> # v6.3+
Fixes: b64be6836993c43 ("ARC: atomics: implement relaxed variants")
Signed-off-by: Pavel Kozlov <pavel.kozlov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
[vgupta: tweaked the changelog and added Fixes tag]
|