From fb51ccbf217c1c994607b6519c7d85250928553d Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Fri, 4 Nov 2011 09:45:59 +0100 Subject: PCI: Rework config space blocking services pci_block_user_cfg_access was designed for the use case that a single context, the IPR driver, temporarily delays user space accesses to the config space via sysfs. This assumption became invalid by the time pci_dev_reset was added as locking instance. Today, if you run two loops in parallel that reset the same device via sysfs, you end up with a kernel BUG as pci_block_user_cfg_access detect the broken assumption. This reworks the pci_block_user_cfg_access to a sleeping service pci_cfg_access_lock and an atomic-compatible variant called pci_cfg_access_trylock. The former not only blocks user space access as before but also waits if access was already locked. The latter service just returns false in this case, allowing the caller to resolve the conflict instead of raising a BUG. Adaptions of the ipr driver were originally written by Brian King. Acked-by: Brian King Acked-by: Michael S. Tsirkin Signed-off-by: Jan Kiszka Signed-off-by: Jesse Barnes --- drivers/uio/uio_pci_generic.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'drivers/uio') diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c index 02bd47bdee1..56d00c6258f 100644 --- a/drivers/uio/uio_pci_generic.c +++ b/drivers/uio/uio_pci_generic.c @@ -55,7 +55,8 @@ static irqreturn_t irqhandler(int irq, struct uio_info *info) BUILD_BUG_ON(PCI_COMMAND % 4); BUILD_BUG_ON(PCI_COMMAND + 2 != PCI_STATUS); - pci_block_user_cfg_access(pdev); + if (!pci_cfg_access_trylock(pdev)) + goto error; /* Read both command and status registers in a single 32-bit operation. * Note: we could cache the value for command and move the status read @@ -79,7 +80,7 @@ static irqreturn_t irqhandler(int irq, struct uio_info *info) ret = IRQ_HANDLED; done: - pci_unblock_user_cfg_access(pdev); + pci_cfg_access_lock(pdev); return ret; } @@ -91,7 +92,7 @@ static int __devinit verify_pci_2_3(struct pci_dev *pdev) u16 orig, new; int err = 0; - pci_block_user_cfg_access(pdev); + pci_cfg_access_lock(pdev); pci_read_config_word(pdev, PCI_COMMAND, &orig); pci_write_config_word(pdev, PCI_COMMAND, orig ^ PCI_COMMAND_INTX_DISABLE); @@ -114,7 +115,7 @@ static int __devinit verify_pci_2_3(struct pci_dev *pdev) /* Now restore the original value. */ pci_write_config_word(pdev, PCI_COMMAND, orig); err: - pci_unblock_user_cfg_access(pdev); + pci_cfg_access_unlock(pdev); return err; } -- cgit v1.2.3-70-g09d2 From 2502dbdfc878a801b5e6d0b6901c334f4051ca39 Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Fri, 4 Nov 2011 09:46:01 +0100 Subject: uio: Convert uio_generic_pci to new intx masking API The new PCI API provides both generic probing for 2.3 masking support and check&mask in the interrupt handler. Acked-by: Michael S. Tsirkin Signed-off-by: Jan Kiszka Signed-off-by: Jesse Barnes --- drivers/uio/uio_pci_generic.c | 79 ++++--------------------------------------- 1 file changed, 7 insertions(+), 72 deletions(-) (limited to 'drivers/uio') diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c index 56d00c6258f..0bd08ef2b39 100644 --- a/drivers/uio/uio_pci_generic.c +++ b/drivers/uio/uio_pci_generic.c @@ -45,78 +45,12 @@ to_uio_pci_generic_dev(struct uio_info *info) static irqreturn_t irqhandler(int irq, struct uio_info *info) { struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info); - struct pci_dev *pdev = gdev->pdev; - irqreturn_t ret = IRQ_NONE; - u32 cmd_status_dword; - u16 origcmd, newcmd, status; - - /* We do a single dword read to retrieve both command and status. - * Document assumptions that make this possible. */ - BUILD_BUG_ON(PCI_COMMAND % 4); - BUILD_BUG_ON(PCI_COMMAND + 2 != PCI_STATUS); - - if (!pci_cfg_access_trylock(pdev)) - goto error; - - /* Read both command and status registers in a single 32-bit operation. - * Note: we could cache the value for command and move the status read - * out of the lock if there was a way to get notified of user changes - * to command register through sysfs. Should be good for shared irqs. */ - pci_read_config_dword(pdev, PCI_COMMAND, &cmd_status_dword); - origcmd = cmd_status_dword; - status = cmd_status_dword >> 16; - - /* Check interrupt status register to see whether our device - * triggered the interrupt. */ - if (!(status & PCI_STATUS_INTERRUPT)) - goto done; - - /* We triggered the interrupt, disable it. */ - newcmd = origcmd | PCI_COMMAND_INTX_DISABLE; - if (newcmd != origcmd) - pci_write_config_word(pdev, PCI_COMMAND, newcmd); - /* UIO core will signal the user process. */ - ret = IRQ_HANDLED; -done: - - pci_cfg_access_lock(pdev); - return ret; -} + if (!pci_check_and_mask_intx(gdev->pdev)) + return IRQ_NONE; -/* Verify that the device supports Interrupt Disable bit in command register, - * per PCI 2.3, by flipping this bit and reading it back: this bit was readonly - * in PCI 2.2. */ -static int __devinit verify_pci_2_3(struct pci_dev *pdev) -{ - u16 orig, new; - int err = 0; - - pci_cfg_access_lock(pdev); - pci_read_config_word(pdev, PCI_COMMAND, &orig); - pci_write_config_word(pdev, PCI_COMMAND, - orig ^ PCI_COMMAND_INTX_DISABLE); - pci_read_config_word(pdev, PCI_COMMAND, &new); - /* There's no way to protect against - * hardware bugs or detect them reliably, but as long as we know - * what the value should be, let's go ahead and check it. */ - if ((new ^ orig) & ~PCI_COMMAND_INTX_DISABLE) { - err = -EBUSY; - dev_err(&pdev->dev, "Command changed from 0x%x to 0x%x: " - "driver or HW bug?\n", orig, new); - goto err; - } - if (!((new ^ orig) & PCI_COMMAND_INTX_DISABLE)) { - dev_warn(&pdev->dev, "Device does not support " - "disabling interrupts: unable to bind.\n"); - err = -ENODEV; - goto err; - } - /* Now restore the original value. */ - pci_write_config_word(pdev, PCI_COMMAND, orig); -err: - pci_cfg_access_unlock(pdev); - return err; + /* UIO core will signal the user process. */ + return IRQ_HANDLED; } static int __devinit probe(struct pci_dev *pdev, @@ -139,9 +73,10 @@ static int __devinit probe(struct pci_dev *pdev, return -ENODEV; } - err = verify_pci_2_3(pdev); - if (err) + if (!pci_intx_mask_supported(pdev)) { + err = -ENODEV; goto err_verify; + } gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL); if (!gdev) { -- cgit v1.2.3-70-g09d2