From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Palmer Dabbelt <palmerdabbelt@google.com>,
Sasha Levin <sashal@kernel.org>,
linux-riscv@lists.infradead.org
Subject: [PATCH AUTOSEL 5.4 33/34] RISC-V: Upgrade smp_mb__after_spinlock() to iorw,iorw
Date: Mon, 20 Jul 2020 17:38:06 -0400 [thread overview]
Message-ID: <20200720213807.407380-33-sashal@kernel.org> (raw)
In-Reply-To: <20200720213807.407380-1-sashal@kernel.org>
From: Palmer Dabbelt <palmerdabbelt@google.com>
[ Upstream commit 38b7c2a3ffb1fce8358ddc6006cfe5c038ff9963 ]
While digging through the recent mmiowb preemption issue it came up that
we aren't actually preventing IO from crossing a scheduling boundary.
While it's a bit ugly to overload smp_mb__after_spinlock() with this
behavior, it's what PowerPC is doing so there's some precedent.
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/riscv/include/asm/barrier.h | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/include/asm/barrier.h b/arch/riscv/include/asm/barrier.h
index 3f1737f301ccb..d0e24aaa2aa06 100644
--- a/arch/riscv/include/asm/barrier.h
+++ b/arch/riscv/include/asm/barrier.h
@@ -58,8 +58,16 @@ do { \
* The AQ/RL pair provides a RCpc critical section, but there's not really any
* way we can take advantage of that here because the ordering is only enforced
* on that one lock. Thus, we're just doing a full fence.
+ *
+ * Since we allow writeX to be called from preemptive regions we need at least
+ * an "o" in the predecessor set to ensure device writes are visible before the
+ * task is marked as available for scheduling on a new hart. While I don't see
+ * any concrete reason we need a full IO fence, it seems safer to just upgrade
+ * this in order to avoid any IO crossing a scheduling boundary. In both
+ * instances the scheduler pairs this with an mb(), so nothing is necessary on
+ * the new hart.
*/
-#define smp_mb__after_spinlock() RISCV_FENCE(rw,rw)
+#define smp_mb__after_spinlock() RISCV_FENCE(iorw,iorw)
#include <asm-generic/barrier.h>
--
2.25.1
next prev parent reply other threads:[~2020-07-20 21:42 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-20 21:37 [PATCH AUTOSEL 5.4 01/34] HID: i2c-hid: add Mediacom FlexBook edge13 to descriptor override Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 02/34] HID: alps: support devices with report id 2 Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 03/34] HID: steam: fixes race in handling device list Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 04/34] HID: apple: Disable Fn-key key-re-mapping on clone keyboards Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 05/34] dmaengine: tegra210-adma: Fix runtime PM imbalance on error Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 06/34] Input: add `SW_MACHINE_COVER` Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 07/34] ARM: dts: n900: remove mmc1 card detect gpio Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 08/34] spi: mediatek: use correct SPI_CFG2_REG MACRO Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 09/34] regmap: dev_get_regmap_match(): fix string comparison Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 10/34] hwmon: (aspeed-pwm-tacho) Avoid possible buffer overflow Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 11/34] dmaengine: fsl-edma: fix wrong tcd endianness for big-endian cpu Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 12/34] dmaengine: ioat setting ioat timeout as module parameter Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 13/34] Input: synaptics - enable InterTouch for ThinkPad X1E 1st gen Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 14/34] Input: elan_i2c - only increment wakeup count on touch Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 15/34] usb: dwc3: pci: add support for the Intel Tiger Lake PCH -H variant Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 16/34] usb: dwc3: pci: add support for the Intel Jasper Lake Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 17/34] usb: gadget: udc: gr_udc: fix memleak on error handling path in gr_ep_init() Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 18/34] usb: cdns3: ep0: fix some endian issues Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 19/34] usb: cdns3: trace: " Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 20/34] hwmon: (adm1275) Make sure we are reading enough data for different chips Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 21/34] drm/amdgpu/gfx10: fix race condition for kiq Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 22/34] drm/amdgpu: fix preemption unit test Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 23/34] hwmon: (nct6775) Accept PECI Calibration as temperature source for NCT6798D Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 24/34] platform/x86: ISST: Add new PCI device ids Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 25/34] platform/x86: asus-wmi: allow BAT1 battery name Sasha Levin
2020-07-20 21:37 ` [PATCH AUTOSEL 5.4 26/34] hwmon: (scmi) Fix potential buffer overflow in scmi_hwmon_probe() Sasha Levin
2020-07-20 21:38 ` [PATCH AUTOSEL 5.4 27/34] ALSA: hda/realtek - fixup for yet another Intel reference board Sasha Levin
2020-07-20 21:38 ` [PATCH AUTOSEL 5.4 28/34] drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling Sasha Levin
2020-07-20 21:38 ` [PATCH AUTOSEL 5.4 29/34] arm64: Use test_tsk_thread_flag() for checking TIF_SINGLESTEP Sasha Levin
2020-07-20 21:38 ` [PATCH AUTOSEL 5.4 30/34] x86: math-emu: Fix up 'cmp' insn for clang ias Sasha Levin
2020-07-20 21:38 ` [PATCH AUTOSEL 5.4 31/34] asm-generic/mmiowb: Allow mmiowb_set_pending() when preemptible() Sasha Levin
2020-07-20 21:38 ` [PATCH AUTOSEL 5.4 32/34] drivers/perf: Prevent forced unbinding of PMU drivers Sasha Levin
2020-07-20 21:38 ` Sasha Levin [this message]
2020-07-20 21:38 ` [PATCH AUTOSEL 5.4 34/34] SUNRPC reverting d03727b248d0 ("NFSv4 fix CLOSE not waiting for direct IO compeletion") Sasha Levin
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