From feadf7c0a1a7c08c74bebb4a13b755f8c40e3bbc Mon Sep 17 00:00:00 2001 From: Gavin Shan Date: Mon, 17 Sep 2012 04:34:27 +0000 Subject: [PATCH] powerpc/eeh: Lock module while handling EEH event The EEH core is talking with the PCI device driver to determine the action (purely reset, or PCI device removal). During the period, the driver might be unloaded and in turn causes kernel crash as follows: EEH: Detected PCI bus error on PHB#4-PE#10000 EEH: This PCI device has failed 3 times in the last hour lpfc 0004:01:00.0: 0:2710 PCI channel disable preparing for reset Unable to handle kernel paging request for data at address 0x00000490 Faulting instruction address: 0xd00000000e682c90 cpu 0x1: Vector: 300 (Data Access) at [c000000fc75ffa20] pc: d00000000e682c90: .lpfc_io_error_detected+0x30/0x240 [lpfc] lr: d00000000e682c8c: .lpfc_io_error_detected+0x2c/0x240 [lpfc] sp: c000000fc75ffca0 msr: 8000000000009032 dar: 490 dsisr: 40000000 current = 0xc000000fc79b88b0 paca = 0xc00000000edb0380 softe: 0 irq_happened: 0x00 pid = 3386, comm = eehd enter ? for help [c000000fc75ffca0] c000000fc75ffd30 (unreliable) [c000000fc75ffd30] c00000000004fd3c .eeh_report_error+0x7c/0xf0 [c000000fc75ffdc0] c00000000004ee00 .eeh_pe_dev_traverse+0xa0/0x180 [c000000fc75ffe70] c00000000004ffd8 .eeh_handle_event+0x68/0x300 [c000000fc75fff00] c0000000000503a0 .eeh_event_handler+0x130/0x1a0 [c000000fc75fff90] c000000000020138 .kernel_thread+0x54/0x70 1:mon> The patch increases the reference of the corresponding driver modules while EEH core does the negotiation with PCI device driver so that the corresponding driver modules can't be unloaded during the period and we're safe to refer the callbacks. Cc: stable@vger.kernel.org Reported-by: Alexey Kardashevskiy Signed-off-by: Gavin Shan Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/platforms/pseries/eeh_driver.c | 91 ++++++++++++++++----- 1 file changed, 70 insertions(+), 21 deletions(-) diff --git a/arch/powerpc/platforms/pseries/eeh_driver.c b/arch/powerpc/platforms/pseries/eeh_driver.c index 37c2cf743133..a3fefb61097c 100644 --- a/arch/powerpc/platforms/pseries/eeh_driver.c +++ b/arch/powerpc/platforms/pseries/eeh_driver.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include #include @@ -47,6 +48,41 @@ static inline const char *eeh_pcid_name(struct pci_dev *pdev) return ""; } +/** + * eeh_pcid_get - Get the PCI device driver + * @pdev: PCI device + * + * The function is used to retrieve the PCI device driver for + * the indicated PCI device. Besides, we will increase the reference + * of the PCI device driver to prevent that being unloaded on + * the fly. Otherwise, kernel crash would be seen. + */ +static inline struct pci_driver *eeh_pcid_get(struct pci_dev *pdev) +{ + if (!pdev || !pdev->driver) + return NULL; + + if (!try_module_get(pdev->driver->driver.owner)) + return NULL; + + return pdev->driver; +} + +/** + * eeh_pcid_put - Dereference on the PCI device driver + * @pdev: PCI device + * + * The function is called to do dereference on the PCI device + * driver of the indicated PCI device. + */ +static inline void eeh_pcid_put(struct pci_dev *pdev) +{ + if (!pdev || !pdev->driver) + return; + + module_put(pdev->driver->driver.owner); +} + #if 0 static void print_device_node_tree(struct pci_dn *pdn, int dent) { @@ -128,23 +164,24 @@ static void *eeh_report_error(void *data, void *userdata) struct eeh_dev *edev = (struct eeh_dev *)data; struct pci_dev *dev = eeh_dev_to_pci_dev(edev); enum pci_ers_result rc, *res = userdata; - struct pci_driver *driver = dev->driver; + struct pci_driver *driver; /* We might not have the associated PCI device, * then we should continue for next one. */ if (!dev) return NULL; - dev->error_state = pci_channel_io_frozen; - if (!driver) - return NULL; + driver = eeh_pcid_get(dev); + if (!driver) return NULL; eeh_disable_irq(dev); if (!driver->err_handler || - !driver->err_handler->error_detected) + !driver->err_handler->error_detected) { + eeh_pcid_put(dev); return NULL; + } rc = driver->err_handler->error_detected(dev, pci_channel_io_frozen); @@ -152,6 +189,7 @@ static void *eeh_report_error(void *data, void *userdata) if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc; if (*res == PCI_ERS_RESULT_NONE) *res = rc; + eeh_pcid_put(dev); return NULL; } @@ -171,12 +209,14 @@ static void *eeh_report_mmio_enabled(void *data, void *userdata) enum pci_ers_result rc, *res = userdata; struct pci_driver *driver; - if (!dev) return NULL; + driver = eeh_pcid_get(dev); + if (!driver) return NULL; - if (!(driver = dev->driver) || - !driver->err_handler || - !driver->err_handler->mmio_enabled) + if (!driver->err_handler || + !driver->err_handler->mmio_enabled) { + eeh_pcid_put(dev); return NULL; + } rc = driver->err_handler->mmio_enabled(dev); @@ -184,6 +224,7 @@ static void *eeh_report_mmio_enabled(void *data, void *userdata) if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc; if (*res == PCI_ERS_RESULT_NONE) *res = rc; + eeh_pcid_put(dev); return NULL; } @@ -204,16 +245,19 @@ static void *eeh_report_reset(void *data, void *userdata) enum pci_ers_result rc, *res = userdata; struct pci_driver *driver; - if (!dev || !(driver = dev->driver)) - return NULL; - + if (!dev) return NULL; dev->error_state = pci_channel_io_normal; + driver = eeh_pcid_get(dev); + if (!driver) return NULL; + eeh_enable_irq(dev); if (!driver->err_handler || - !driver->err_handler->slot_reset) + !driver->err_handler->slot_reset) { + eeh_pcid_put(dev); return NULL; + } rc = driver->err_handler->slot_reset(dev); if ((*res == PCI_ERS_RESULT_NONE) || @@ -221,6 +265,7 @@ static void *eeh_report_reset(void *data, void *userdata) if (*res == PCI_ERS_RESULT_DISCONNECT && rc == PCI_ERS_RESULT_NEED_RESET) *res = rc; + eeh_pcid_put(dev); return NULL; } @@ -240,20 +285,22 @@ static void *eeh_report_resume(void *data, void *userdata) struct pci_driver *driver; if (!dev) return NULL; - dev->error_state = pci_channel_io_normal; - if (!(driver = dev->driver)) - return NULL; + driver = eeh_pcid_get(dev); + if (!driver) return NULL; eeh_enable_irq(dev); if (!driver->err_handler || - !driver->err_handler->resume) + !driver->err_handler->resume) { + eeh_pcid_put(dev); return NULL; + } driver->err_handler->resume(dev); + eeh_pcid_put(dev); return NULL; } @@ -272,20 +319,22 @@ static void *eeh_report_failure(void *data, void *userdata) struct pci_driver *driver; if (!dev) return NULL; - dev->error_state = pci_channel_io_perm_failure; - if (!(driver = dev->driver)) - return NULL; + driver = eeh_pcid_get(dev); + if (!driver) return NULL; eeh_disable_irq(dev); if (!driver->err_handler || - !driver->err_handler->error_detected) + !driver->err_handler->error_detected) { + eeh_pcid_put(dev); return NULL; + } driver->err_handler->error_detected(dev, pci_channel_io_perm_failure); + eeh_pcid_put(dev); return NULL; } -- 2.20.1