On 18 December 2015 at 14:15, Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> wrote: > On Mon, 14 Dec, at 11:40:24AM, Ard Biesheuvel wrote: >> The UEFI spec does not require interrupts to be disabled when invoking >> runtime services. The reason we have been doing so is because EFI pstore >> may call SetVariable() from interrupt context, which may result in deadlock >> if another runtime services call was in progress on the same cpu. > >> The EFI pstore has already been updated to use a non-blocking path and fail >> gracefully rather than spin forever, so we can update the ordinary blocking >> wrappers to run with interrupts enabled instead. This aims to prevent excessive >> interrupt latencies on uniprocessor platforms with slow variable stores. >> >> Changes since v2: >> - folded Matt's suggestion for patch #4, to bail rather than try to trigger a >> garbage collection in the nonblocking case when there is insufficient space >> - rebased onto v4.4-rc5 >> >> Changes since v1: >> - added nonblocking QueryVariableInfo() wrapper variant, and updated >> efi_query_variable_store() to use it when called in nonblocking context >> - add patch to drop the rtc_lock spinlock >> - add patch to drop redundant efi_set_variable_nonblocking_t typedef >> - drop BUG_ONs in patch #7 >> >> Ard Biesheuvel (7): >> efi: expose non-blocking set_variable() wrapper to efivars >> efi: remove redundant efi_set_variable_nonblocking prototype >> efi: runtime-wrappers: add a nonblocking version of QueryVariableInfo >> efi: add nonblocking option to efi_query_variable_store() >> efi: runtime-wrappers: remove out of date comment regarding in_nmi() >> efi: runtime-wrapper: get rid of the rtc_lock spinlock >> efi: runtime-wrappers: run UEFI Runtime Services with interrupts >> enabled >> >> arch/x86/platform/efi/quirks.c | 33 +++++- >> drivers/firmware/efi/efi.c | 1 + >> drivers/firmware/efi/runtime-wrappers.c | 115 +++++++------------- >> drivers/firmware/efi/vars.c | 16 ++- >> include/linux/efi.h | 21 ++-- >> 5 files changed, 100 insertions(+), 86 deletions(-) > > Thanks Ard, this all looks good to me. I've queued this up. It's a > little late for v4.5 now, so this will probably be targeting v4.6. Either is fine by me, as long as it is in the pipeline. Thanks, Ard. -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
