From 290c13b7d70b0b396509bf20787ab75ccb057cb7 Mon Sep 17 00:00:00 2001 From: Jan Hoffmann Date: Sun, 13 Mar 2022 22:14:38 +0100 Subject: ltq-vdsl-mei: add locking to interrupt handler Some users noticed repeated resyncs at random intervals, which go away when the MEI driver is configured to use polling instead of interrupts. Debugging shows that this seems to be caused by concurrent calls to MEI_ReadMailbox (in the interrupt handler) and MEI_WriteMailbox. This appears to be mostly triggered when there is an interrupt for vectoring error reports. In polling mode, calls to MEI_ReadMailbox are protected by the same semaphore as is used in MEI_WriteMailbox. When interrupts are used, MEI_WriteMailbox appears to rely on MEI_DisableDeviceInt and MEI_EnableDeviceInt to provide mutual exclusion with the interrupt handler. These functions mask/unmask interrupts, and there is an additional check of the mask in the interrupt handler itself. However, this is not sufficient on systems with SMP, as the interrupt handler may be running in parallel, and could already be past the interrupt mask check at this point. This adds a lock to the interrupt handler, and also acquires this lock in MEI_DisableDeviceInt. This should make sure that after a call to MEI_DisableDeviceInt the interrupt is masked, and the interrupt handler is either not running, has alread finished its work, or is still before the interrupt mask check, and is thus going to detect the change. Tested-by: Martin Blumenstingl Signed-off-by: Jan Hoffmann (cherry picked from commit 17004245534731ab03c9a8683208e84d9c399979) --- package/kernel/lantiq/ltq-vdsl-mei/Makefile | 2 +- .../ltq-vdsl-mei/patches/200-interrupt-lock.patch | 45 ++++++++++++++++++++++ 2 files changed, 46 insertions(+), 1 deletion(-) create mode 100644 package/kernel/lantiq/ltq-vdsl-mei/patches/200-interrupt-lock.patch diff --git a/package/kernel/lantiq/ltq-vdsl-mei/Makefile b/package/kernel/lantiq/ltq-vdsl-mei/Makefile index d4a5ea720b..b7060eb2b4 100644 --- a/package/kernel/lantiq/ltq-vdsl-mei/Makefile +++ b/package/kernel/lantiq/ltq-vdsl-mei/Makefile @@ -9,7 +9,7 @@ include $(INCLUDE_DIR)/kernel.mk PKG_NAME:=ltq-vdsl-vr9-mei PKG_VERSION:=1.5.17.6 -PKG_RELEASE:=5 +PKG_RELEASE:=6 PKG_BASE_NAME:=drv_mei_cpe PKG_SOURCE:=$(PKG_BASE_NAME)-$(PKG_VERSION).tar.gz diff --git a/package/kernel/lantiq/ltq-vdsl-mei/patches/200-interrupt-lock.patch b/package/kernel/lantiq/ltq-vdsl-mei/patches/200-interrupt-lock.patch new file mode 100644 index 0000000000..a677ccec55 --- /dev/null +++ b/package/kernel/lantiq/ltq-vdsl-mei/patches/200-interrupt-lock.patch @@ -0,0 +1,45 @@ +--- a/src/drv_mei_cpe_common.c ++++ b/src/drv_mei_cpe_common.c +@@ -104,6 +104,8 @@ IFX_uint32_t MEI_FsmStateSetMsgPreAction + MEI_DEVCFG_DATA_T MEI_DevCfgData; + #endif + ++static DEFINE_SPINLOCK(MEI_InterruptLock); ++ + /* ============================================================================ + Proc-FS and debug variable definitions + ========================================================================= */ +@@ -2134,6 +2136,9 @@ IFX_int32_t MEI_ProcessIntPerIrq(MEIX_CN + #if (MEI_SUPPORT_DEBUG_STREAMS == 1) + IFX_int_t extraDbgStreamLoop = 0; + #endif ++ unsigned long flags; ++ ++ spin_lock_irqsave(&MEI_InterruptLock, flags); + + /* get the actual chip device from the list and step through the VRX devices */ + while(pNextXCntrl) +@@ -2167,6 +2172,8 @@ IFX_int32_t MEI_ProcessIntPerIrq(MEIX_CN + } + #endif + ++ spin_unlock_irqrestore(&MEI_InterruptLock, flags); ++ + return meiIntCnt; + } + +@@ -2639,9 +2646,14 @@ IFX_int32_t MEI_MsgSendPreAction( + */ + IFX_void_t MEI_DisableDeviceInt(MEI_DEV_T *pMeiDev) + { ++ unsigned long flags; ++ spin_lock_irqsave(&MEI_InterruptLock, flags); ++ + MEI_MaskInterrupts( &pMeiDev->meiDrvCntrl, + ME_ARC2ME_INTERRUPT_MASK_ALL); + ++ spin_unlock_irqrestore(&MEI_InterruptLock, flags); ++ + return; + } + -- cgit v1.2.3