From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1164714AbdEYALl (ORCPT ); Wed, 24 May 2017 20:11:41 -0400 Received: from mail-pf0-f181.google.com ([209.85.192.181]:33386 "EHLO mail-pf0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1164672AbdEYALg (ORCPT ); Wed, 24 May 2017 20:11:36 -0400 From: Brian Norris To: Ganapathi Bhat , Nishant Sarmukadam Cc: , Dmitry Torokhov , Amitkumar Karwar , Kalle Valo , linux-wireless@vger.kernel.org, Brian Norris Subject: [PATCH 01/14] mwifiex: pcie: properly synchronize, disable interrupts in driver callbacks Date: Wed, 24 May 2017 17:11:06 -0700 Message-Id: <20170525001119.64791-1-briannorris@chromium.org> X-Mailer: git-send-email 2.13.0.219.gdb65acc882-goog Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It seems that the implicit assumption of the mwifiex {enable,disable}_int() callbacks is that after ->disable_int(), all interrupt handling should be complete (synchronized) and not fire again until after ->enable_int(). Also, interrupts should not be serviced until after the first ->enable_int(). However, the PCIe driver does none of this. First, the existing interrupt mask programming appears to only have an effect for legacy interrupts. It doesn't actually prevent MSI/MSI-X interrupts. Second, even when it might mask interrupts, we're doing nothing to ensure that pending IRQs have finished processing; they could be already in-flight when a CPU masks them. Another quirk of this driver's design is the use of a racy "surprise_removed" check in mwifiex_pcie_interrupt(). This appears to act like a racy poor-man's version of masking our interrupts -- it allows us to short-circuit the ISR if it fires when we're not prepared to handle more work. We can resolve this all by: (a) disabling our IRQs after requesting them (b) call {enable,disable}_irq() in the {enable,disable}_int() callbacks (c) remove the racy '->surprise_removed' hack from mwifiex_pcie_interrupt() (d) document the effect (or lack thereof) of PCIE_HOST_INT_MASK, to clarify and possibly prevent future misuse Along the way, I decided to use underscores to prefix the driver-private forms of "disabling interrupts" (instead of the awkward "_noerr" suffix used already), partly to discourage their use. Signed-off-by: Brian Norris --- drivers/net/wireless/marvell/mwifiex/pcie.c | 70 ++++++++++++++++++++--------- 1 file changed, 49 insertions(+), 21 deletions(-) diff --git a/drivers/net/wireless/marvell/mwifiex/pcie.c b/drivers/net/wireless/marvell/mwifiex/pcie.c index 394224d6c219..ea75315bf19d 100644 --- a/drivers/net/wireless/marvell/mwifiex/pcie.c +++ b/drivers/net/wireless/marvell/mwifiex/pcie.c @@ -505,12 +505,10 @@ static int mwifiex_pm_wakeup_card_complete(struct mwifiex_adapter *adapter) } /* - * This function disables the host interrupt. - * - * The host interrupt mask is read, the disable bit is reset and - * written back to the card host interrupt mask register. + * This function masks the host interrupt. Effective only for legacy PCI + * interrupts. */ -static int mwifiex_pcie_disable_host_int(struct mwifiex_adapter *adapter) +static int __mwifiex_pcie_disable_host_int(struct mwifiex_adapter *adapter) { if (mwifiex_pcie_ok_to_access_hw(adapter)) { if (mwifiex_write_reg(adapter, PCIE_HOST_INT_MASK, @@ -525,18 +523,30 @@ static int mwifiex_pcie_disable_host_int(struct mwifiex_adapter *adapter) return 0; } -static void mwifiex_pcie_disable_host_int_noerr(struct mwifiex_adapter *adapter) +/* + * Disable interrupts, synchronizing with any outstanding interrupts. + */ +static void mwifiex_pcie_disable_host_int(struct mwifiex_adapter *adapter) { - WARN_ON(mwifiex_pcie_disable_host_int(adapter)); + struct pcie_service_card *card = adapter->card; + int i; + + WARN_ON(__mwifiex_pcie_disable_host_int(adapter)); + + if (card->msix_enable) { + for (i = 0; i < MWIFIEX_NUM_MSIX_VECTORS; i++) { + disable_irq(card->msix_entries[i].vector); + } + } else { + disable_irq(card->dev->irq); + } } /* - * This function enables the host interrupt. - * - * The host interrupt enable mask is written to the card - * host interrupt mask register. + * This function unmasks the host interrupt. Effective only for legacy PCI + * interrupts. */ -static int mwifiex_pcie_enable_host_int(struct mwifiex_adapter *adapter) +static int __mwifiex_pcie_enable_host_int(struct mwifiex_adapter *adapter) { if (mwifiex_pcie_ok_to_access_hw(adapter)) { /* Simply write the mask to the register */ @@ -551,6 +561,26 @@ static int mwifiex_pcie_enable_host_int(struct mwifiex_adapter *adapter) return 0; } +static int mwifiex_pcie_enable_host_int(struct mwifiex_adapter *adapter) +{ + struct pcie_service_card *card = adapter->card; + int i, ret; + + ret = __mwifiex_pcie_enable_host_int(adapter); + if (ret) + return ret; + + if (card->msix_enable) { + for (i = 0; i < MWIFIEX_NUM_MSIX_VECTORS; i++) { + enable_irq(card->msix_entries[i].vector); + } + } else { + enable_irq(card->dev->irq); + } + + return 0; +} + /* * This function initializes TX buffer ring descriptors */ @@ -1738,7 +1768,7 @@ static int mwifiex_pcie_process_cmd_complete(struct mwifiex_adapter *adapter) while (reg->sleep_cookie && (count++ < 10) && mwifiex_pcie_ok_to_access_hw(adapter)) usleep_range(50, 60); - mwifiex_pcie_enable_host_int(adapter); + __mwifiex_pcie_enable_host_int(adapter); mwifiex_process_sleep_confirm_resp(adapter, skb->data, skb->len); } else { @@ -2081,7 +2111,7 @@ static int mwifiex_prog_fw_w_helper(struct mwifiex_adapter *adapter, "info: Downloading FW image (%d bytes)\n", firmware_len); - if (mwifiex_pcie_disable_host_int(adapter)) { + if (__mwifiex_pcie_disable_host_int(adapter)) { mwifiex_dbg(adapter, ERROR, "%s: Disabling interrupts failed.\n", __func__); return -1; @@ -2335,8 +2365,7 @@ static void mwifiex_interrupt_status(struct mwifiex_adapter *adapter, if ((pcie_ireg == 0xFFFFFFFF) || !pcie_ireg) return; - - mwifiex_pcie_disable_host_int(adapter); + __mwifiex_pcie_disable_host_int(adapter); /* Clear the pending interrupts */ if (mwifiex_write_reg(adapter, PCIE_HOST_INT_STATUS, @@ -2387,9 +2416,6 @@ static irqreturn_t mwifiex_pcie_interrupt(int irq, void *context) } adapter = card->adapter; - if (adapter->surprise_removed) - goto exit; - if (card->msix_enable) mwifiex_interrupt_status(adapter, ctx->msg_id); else @@ -2494,7 +2520,7 @@ static int mwifiex_process_pcie_int(struct mwifiex_adapter *adapter) "info: cmd_sent=%d data_sent=%d\n", adapter->cmd_sent, adapter->data_sent); if (!card->msi_enable && adapter->ps_state != PS_STATE_SLEEP) - mwifiex_pcie_enable_host_int(adapter); + __mwifiex_pcie_enable_host_int(adapter); return 0; } @@ -3055,6 +3081,7 @@ static int mwifiex_pcie_request_irq(struct mwifiex_adapter *adapter) &card->msix_ctx[i]); if (ret) break; + disable_irq(card->msix_entries[i].vector); } if (ret) { @@ -3087,6 +3114,7 @@ static int mwifiex_pcie_request_irq(struct mwifiex_adapter *adapter) pr_err("request_irq failed: ret=%d\n", ret); return -1; } + disable_irq(pdev->irq); return 0; } @@ -3244,7 +3272,7 @@ static struct mwifiex_if_ops pcie_ops = { .register_dev = mwifiex_register_dev, .unregister_dev = mwifiex_unregister_dev, .enable_int = mwifiex_pcie_enable_host_int, - .disable_int = mwifiex_pcie_disable_host_int_noerr, + .disable_int = mwifiex_pcie_disable_host_int, .process_int_status = mwifiex_process_int_status, .host_to_card = mwifiex_pcie_host_to_card, .wakeup = mwifiex_pm_wakeup_card, -- 2.13.0.219.gdb65acc882-goog