Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752498AbdFAQWQ (ORCPT ); Thu, 1 Jun 2017 12:22:16 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33485 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752074AbdFAPox (ORCPT ); Thu, 1 Jun 2017 11:44:53 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Felix Fietkau" , "Kalle Valo" Date: Thu, 01 Jun 2017 16:43:16 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 106/212] ath9k: fix race condition in enabling/disabling IRQs In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6525 Lines: 209 3.16.44-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Felix Fietkau commit 3a5e969bb2f6692a256352649355d56d018d6b88 upstream. The code currently relies on refcounting to disable IRQs from within the IRQ handler and re-enabling them again after the tasklet has run. However, due to race conditions sometimes the IRQ handler might be called twice, or the tasklet may not run at all (if interrupted in the middle of a reset). This can cause nasty imbalances in the irq-disable refcount which will get the driver permanently stuck until the entire radio has been stopped and started again (ath_reset will not recover from this). Instead of using this fragile logic, change the code to ensure that running the irq handler during tasklet processing is safe, and leave the refcount untouched. Signed-off-by: Felix Fietkau Signed-off-by: Kalle Valo [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- drivers/net/wireless/ath/ath9k/ath9k.h | 1 + drivers/net/wireless/ath/ath9k/init.c | 1 + drivers/net/wireless/ath/ath9k/mac.c | 44 ++++++++++++++++++++++++++-------- drivers/net/wireless/ath/ath9k/mac.h | 1 + drivers/net/wireless/ath/ath9k/main.c | 27 +++++++++------------ 5 files changed, 48 insertions(+), 26 deletions(-) --- a/drivers/net/wireless/ath/ath9k/ath9k.h +++ b/drivers/net/wireless/ath/ath9k/ath9k.h @@ -709,6 +709,7 @@ struct ath_softc { struct survey_info *cur_survey; struct survey_info survey[ATH9K_NUM_CHANNELS]; + spinlock_t intr_lock; struct tasklet_struct intr_tq; struct tasklet_struct bcon_tasklet; struct ath_hw *sc_ah; --- a/drivers/net/wireless/ath/ath9k/init.c +++ b/drivers/net/wireless/ath/ath9k/init.c @@ -554,6 +554,7 @@ static int ath9k_init_softc(u16 devid, s common->bt_ant_diversity = 1; spin_lock_init(&common->cc_lock); + spin_lock_init(&sc->intr_lock); spin_lock_init(&sc->sc_serial_rw); spin_lock_init(&sc->sc_pm_lock); mutex_init(&sc->mutex); --- a/drivers/net/wireless/ath/ath9k/mac.c +++ b/drivers/net/wireless/ath/ath9k/mac.c @@ -805,21 +805,12 @@ void ath9k_hw_disable_interrupts(struct } EXPORT_SYMBOL(ath9k_hw_disable_interrupts); -void ath9k_hw_enable_interrupts(struct ath_hw *ah) +static void __ath9k_hw_enable_interrupts(struct ath_hw *ah) { struct ath_common *common = ath9k_hw_common(ah); u32 sync_default = AR_INTR_SYNC_DEFAULT; u32 async_mask; - if (!(ah->imask & ATH9K_INT_GLOBAL)) - return; - - if (!atomic_inc_and_test(&ah->intr_ref_cnt)) { - ath_dbg(common, INTERRUPT, "Do not enable IER ref count %d\n", - atomic_read(&ah->intr_ref_cnt)); - return; - } - if (AR_SREV_9340(ah) || AR_SREV_9550(ah) || AR_SREV_9531(ah)) sync_default &= ~AR_INTR_SYNC_HOST1_FATAL; @@ -840,6 +831,39 @@ void ath9k_hw_enable_interrupts(struct a ath_dbg(common, INTERRUPT, "AR_IMR 0x%x IER 0x%x\n", REG_READ(ah, AR_IMR), REG_READ(ah, AR_IER)); } + +void ath9k_hw_resume_interrupts(struct ath_hw *ah) +{ + struct ath_common *common = ath9k_hw_common(ah); + + if (!(ah->imask & ATH9K_INT_GLOBAL)) + return; + + if (atomic_read(&ah->intr_ref_cnt) != 0) { + ath_dbg(common, INTERRUPT, "Do not enable IER ref count %d\n", + atomic_read(&ah->intr_ref_cnt)); + return; + } + + __ath9k_hw_enable_interrupts(ah); +} +EXPORT_SYMBOL(ath9k_hw_resume_interrupts); + +void ath9k_hw_enable_interrupts(struct ath_hw *ah) +{ + struct ath_common *common = ath9k_hw_common(ah); + + if (!(ah->imask & ATH9K_INT_GLOBAL)) + return; + + if (!atomic_inc_and_test(&ah->intr_ref_cnt)) { + ath_dbg(common, INTERRUPT, "Do not enable IER ref count %d\n", + atomic_read(&ah->intr_ref_cnt)); + return; + } + + __ath9k_hw_enable_interrupts(ah); +} EXPORT_SYMBOL(ath9k_hw_enable_interrupts); void ath9k_hw_set_interrupts(struct ath_hw *ah) --- a/drivers/net/wireless/ath/ath9k/mac.h +++ b/drivers/net/wireless/ath/ath9k/mac.h @@ -737,6 +737,7 @@ void ath9k_hw_set_interrupts(struct ath_ void ath9k_hw_enable_interrupts(struct ath_hw *ah); void ath9k_hw_disable_interrupts(struct ath_hw *ah); void ath9k_hw_kill_interrupts(struct ath_hw *ah); +void ath9k_hw_resume_interrupts(struct ath_hw *ah); void ar9002_hw_attach_mac_ops(struct ath_hw *ah); --- a/drivers/net/wireless/ath/ath9k/main.c +++ b/drivers/net/wireless/ath/ath9k/main.c @@ -441,21 +441,20 @@ void ath9k_tasklet(unsigned long data) struct ath_common *common = ath9k_hw_common(ah); enum ath_reset_type type; unsigned long flags; - u32 status = sc->intrstatus; + u32 status; u32 rxmask; + spin_lock_irqsave(&sc->intr_lock, flags); + status = sc->intrstatus; + sc->intrstatus = 0; + spin_unlock_irqrestore(&sc->intr_lock, flags); + ath9k_ps_wakeup(sc); spin_lock(&sc->sc_pcu_lock); if (status & ATH9K_INT_FATAL) { type = RESET_TYPE_FATAL_INT; ath9k_queue_reset(sc, type); - - /* - * Increment the ref. counter here so that - * interrupts are enabled in the reset routine. - */ - atomic_inc(&ah->intr_ref_cnt); ath_dbg(common, RESET, "FATAL: Skipping interrupts\n"); goto out; } @@ -471,11 +470,6 @@ void ath9k_tasklet(unsigned long data) type = RESET_TYPE_BB_WATCHDOG; ath9k_queue_reset(sc, type); - /* - * Increment the ref. counter here so that - * interrupts are enabled in the reset routine. - */ - atomic_inc(&ah->intr_ref_cnt); ath_dbg(common, RESET, "BB_WATCHDOG: Skipping interrupts\n"); goto out; @@ -488,7 +482,6 @@ void ath9k_tasklet(unsigned long data) if ((sc->gtt_cnt >= MAX_GTT_CNT) && !ath9k_hw_check_alive(ah)) { type = RESET_TYPE_TX_GTT; ath9k_queue_reset(sc, type); - atomic_inc(&ah->intr_ref_cnt); ath_dbg(common, RESET, "GTT: Skipping interrupts\n"); goto out; @@ -545,7 +538,7 @@ void ath9k_tasklet(unsigned long data) ath9k_btcoex_handle_interrupt(sc, status); /* re-enable hardware interrupt */ - ath9k_hw_enable_interrupts(ah); + ath9k_hw_resume_interrupts(ah); out: spin_unlock(&sc->sc_pcu_lock); ath9k_ps_restore(sc); @@ -612,7 +605,9 @@ irqreturn_t ath_isr(int irq, void *dev) return IRQ_NONE; /* Cache the status */ - sc->intrstatus = status; + spin_lock(&sc->intr_lock); + sc->intrstatus |= status; + spin_unlock(&sc->intr_lock); if (status & SCHED_INTR) sched = true; @@ -668,7 +663,7 @@ chip_reset: if (sched) { /* turn off every interrupt */ - ath9k_hw_disable_interrupts(ah); + ath9k_hw_kill_interrupts(ah); tasklet_schedule(&sc->intr_tq); }