From: Hillf Danton Date: Tue, 14 May 2019 08:34:19 +0000 (+0800) Subject: arm64: assembler: Update comment above cond_yield_neon() macro X-Git-Tag: v5.4-rc1~913^2~4 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0e4add4ae79e4466ae2a7e7772dfbe39fb28787a;p=platform%2Fkernel%2Flinux-rpi.git arm64: assembler: Update comment above cond_yield_neon() macro Since commit 7faa313f05ca ("arm64: preempt: Fix big-endian when checking preempt count in assembly") both the preempt count and the 'need_resched' flag are checked as part of a single 64-bit load in cond_yield_neon(), so update the stale comment to reflect reality. Cc: Ard Biesheuvel Cc: Dave Martin Cc: Will Deacon Cc: Peter Zijlstra Signed-off-by: Hillf Danton Signed-off-by: Will Deacon --- diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index 039fbd8..92b6b7c 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -718,12 +718,11 @@ USER(\label, ic ivau, \tmp2) // invalidate I line PoU * the output section, any use of such directives is undefined. * * The yield itself consists of the following: - * - Check whether the preempt count is exactly 1, in which case disabling - * preemption once will make the task preemptible. If this is not the case, - * yielding is pointless. - * - Check whether TIF_NEED_RESCHED is set, and if so, disable and re-enable - * kernel mode NEON (which will trigger a reschedule), and branch to the - * yield fixup code. + * - Check whether the preempt count is exactly 1 and a reschedule is also + * needed. If so, calling of preempt_enable() in kernel_neon_end() will + * trigger a reschedule. If it is not the case, yielding is pointless. + * - Disable and re-enable kernel mode NEON, and branch to the yield fixup + * code. * * This macro sequence may clobber all CPU state that is not guaranteed by the * AAPCS to be preserved across an ordinary function call.