* [PATCH] PCI: Mediatek: clear irq status after irq dispathed to avoid reentry @ 2017-12-20 2:52 honghui.zhang at mediatek.com 2017-12-20 3:08 ` Ryder Lee 2017-12-21 0:52 ` Bjorn Helgaas 0 siblings, 2 replies; 4+ messages in thread From: honghui.zhang at mediatek.com @ 2017-12-20 2:52 UTC (permalink / raw) To: linux-arm-kernel From: Honghui Zhang <honghui.zhang@mediatek.com> There maybe a same irq reentry scenario after irq received in current irq handle flow: EP device PCIe host driver EP driver 1. issue an irq 2. received irq 3. clear irq status 4. dispatch irq 5. clear irq source The irq status was not successfully cleared at step 2 since the irq source was not cleared yet. So the PCIe host driver may receive the same irq after step 5. Then there's an irq reentry occurred. Even worse, if the reentry irq was not an irq that EP driver expected, it may not handle the irq. Then we may run into the dead loop from step 2 to step 4. Clear the irq status after irq have been dispatched to avoid the irq reentry. Signed-off-by: Honghui Zhang <honghui.zhang@mediatek.com> --- drivers/pci/host/pcie-mediatek.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/pci/host/pcie-mediatek.c b/drivers/pci/host/pcie-mediatek.c index db93efd..3248771 100644 --- a/drivers/pci/host/pcie-mediatek.c +++ b/drivers/pci/host/pcie-mediatek.c @@ -605,11 +605,11 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) while ((status = readl(port->base + PCIE_INT_STATUS)) & INTX_MASK) { for_each_set_bit_from(bit, &status, PCI_NUM_INTX + INTX_SHIFT) { - /* Clear the INTx */ - writel(1 << bit, port->base + PCIE_INT_STATUS); virq = irq_find_mapping(port->irq_domain, bit - INTX_SHIFT); generic_handle_irq(virq); + /* Clear the INTx */ + writel(1 << bit, port->base + PCIE_INT_STATUS); } } @@ -619,10 +619,10 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) while ((imsi_status = readl(port->base + PCIE_IMSI_STATUS))) { for_each_set_bit(bit, &imsi_status, MTK_MSI_IRQS_NUM) { - /* Clear the MSI */ - writel(1 << bit, port->base + PCIE_IMSI_STATUS); virq = irq_find_mapping(port->msi_domain, bit); generic_handle_irq(virq); + /* Clear the MSI */ + writel(1 << bit, port->base + PCIE_IMSI_STATUS); } } /* Clear MSI interrupt status */ -- 2.6.4 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] PCI: Mediatek: clear irq status after irq dispathed to avoid reentry 2017-12-20 2:52 [PATCH] PCI: Mediatek: clear irq status after irq dispathed to avoid reentry honghui.zhang at mediatek.com @ 2017-12-20 3:08 ` Ryder Lee 2017-12-21 0:52 ` Bjorn Helgaas 1 sibling, 0 replies; 4+ messages in thread From: Ryder Lee @ 2017-12-20 3:08 UTC (permalink / raw) To: linux-arm-kernel On Wed, 2017-12-20 at 10:52 +0800, honghui.zhang at mediatek.com wrote: > From: Honghui Zhang <honghui.zhang@mediatek.com> > > There maybe a same irq reentry scenario after irq received in current > irq handle flow: > EP device PCIe host driver EP driver > 1. issue an irq > 2. received irq > 3. clear irq status > 4. dispatch irq > 5. clear irq source > The irq status was not successfully cleared at step 2 since the irq > source was not cleared yet. So the PCIe host driver may receive the > same irq after step 5. Then there's an irq reentry occurred. > Even worse, if the reentry irq was not an irq that EP driver expected, > it may not handle the irq. Then we may run into the dead loop from > step 2 to step 4. > Clear the irq status after irq have been dispatched to avoid the irq > reentry. > > Signed-off-by: Honghui Zhang <honghui.zhang@mediatek.com> > --- > drivers/pci/host/pcie-mediatek.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/pci/host/pcie-mediatek.c b/drivers/pci/host/pcie-mediatek.c > index db93efd..3248771 100644 > --- a/drivers/pci/host/pcie-mediatek.c > +++ b/drivers/pci/host/pcie-mediatek.c > @@ -605,11 +605,11 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) > > while ((status = readl(port->base + PCIE_INT_STATUS)) & INTX_MASK) { > for_each_set_bit_from(bit, &status, PCI_NUM_INTX + INTX_SHIFT) { > - /* Clear the INTx */ > - writel(1 << bit, port->base + PCIE_INT_STATUS); > virq = irq_find_mapping(port->irq_domain, > bit - INTX_SHIFT); > generic_handle_irq(virq); > + /* Clear the INTx */ > + writel(1 << bit, port->base + PCIE_INT_STATUS); > } > } > > @@ -619,10 +619,10 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) > > while ((imsi_status = readl(port->base + PCIE_IMSI_STATUS))) { > for_each_set_bit(bit, &imsi_status, MTK_MSI_IRQS_NUM) { > - /* Clear the MSI */ > - writel(1 << bit, port->base + PCIE_IMSI_STATUS); > virq = irq_find_mapping(port->msi_domain, bit); > generic_handle_irq(virq); > + /* Clear the MSI */ > + writel(1 << bit, port->base + PCIE_IMSI_STATUS); > } > } > /* Clear MSI interrupt status */ Acked-by: Ryder Lee <ryder.lee@mediatek.com> Thanks. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] PCI: Mediatek: clear irq status after irq dispathed to avoid reentry 2017-12-20 2:52 [PATCH] PCI: Mediatek: clear irq status after irq dispathed to avoid reentry honghui.zhang at mediatek.com 2017-12-20 3:08 ` Ryder Lee @ 2017-12-21 0:52 ` Bjorn Helgaas 2017-12-21 1:37 ` Honghui Zhang 1 sibling, 1 reply; 4+ messages in thread From: Bjorn Helgaas @ 2017-12-21 0:52 UTC (permalink / raw) To: linux-arm-kernel [+cc Lorenzo, please cc him on all drivers/{host,dwc,endpoint} material] Please run "git log --oneline drivers/pci/host/pcie-mediatek.c" and make yours match. Same capitalization, same sentence structure, etc., e.g., PCI: mediatek: Clear IRQ status ... s/dispathed/dispatched/ s/irq/IRQ/ in the summary and all the English text below. On Wed, Dec 20, 2017 at 10:52:14AM +0800, honghui.zhang at mediatek.com wrote: > From: Honghui Zhang <honghui.zhang@mediatek.com> > > There maybe a same irq reentry scenario after irq received in current > irq handle flow: > EP device PCIe host driver EP driver > 1. issue an irq > 2. received irq > 3. clear irq status > 4. dispatch irq > 5. clear irq source > The irq status was not successfully cleared at step 2 since the irq > source was not cleared yet. So the PCIe host driver may receive the > same irq after step 5. Then there's an irq reentry occurred. > Even worse, if the reentry irq was not an irq that EP driver expected, > it may not handle the irq. Then we may run into the dead loop from By "dead loop" I assume you mean "infinite loop"? I don't think it's a deadlock since nothing is waiting. > step 2 to step 4. > Clear the irq status after irq have been dispatched to avoid the irq > reentry. > > Signed-off-by: Honghui Zhang <honghui.zhang@mediatek.com> > --- > drivers/pci/host/pcie-mediatek.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/pci/host/pcie-mediatek.c b/drivers/pci/host/pcie-mediatek.c > index db93efd..3248771 100644 > --- a/drivers/pci/host/pcie-mediatek.c > +++ b/drivers/pci/host/pcie-mediatek.c > @@ -605,11 +605,11 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) > > while ((status = readl(port->base + PCIE_INT_STATUS)) & INTX_MASK) { > for_each_set_bit_from(bit, &status, PCI_NUM_INTX + INTX_SHIFT) { > - /* Clear the INTx */ > - writel(1 << bit, port->base + PCIE_INT_STATUS); > virq = irq_find_mapping(port->irq_domain, > bit - INTX_SHIFT); > generic_handle_irq(virq); > + /* Clear the INTx */ > + writel(1 << bit, port->base + PCIE_INT_STATUS); > } > } > > @@ -619,10 +619,10 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) > > while ((imsi_status = readl(port->base + PCIE_IMSI_STATUS))) { > for_each_set_bit(bit, &imsi_status, MTK_MSI_IRQS_NUM) { > - /* Clear the MSI */ > - writel(1 << bit, port->base + PCIE_IMSI_STATUS); > virq = irq_find_mapping(port->msi_domain, bit); > generic_handle_irq(virq); > + /* Clear the MSI */ > + writel(1 << bit, port->base + PCIE_IMSI_STATUS); > } > } > /* Clear MSI interrupt status */ > -- > 2.6.4 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] PCI: Mediatek: clear irq status after irq dispathed to avoid reentry 2017-12-21 0:52 ` Bjorn Helgaas @ 2017-12-21 1:37 ` Honghui Zhang 0 siblings, 0 replies; 4+ messages in thread From: Honghui Zhang @ 2017-12-21 1:37 UTC (permalink / raw) To: linux-arm-kernel On Wed, 2017-12-20 at 18:52 -0600, Bjorn Helgaas wrote: > [+cc Lorenzo, please cc him on all drivers/{host,dwc,endpoint} material] > > Please run "git log --oneline drivers/pci/host/pcie-mediatek.c" and > make yours match. Same capitalization, same sentence structure, etc., > e.g., > > PCI: mediatek: Clear IRQ status ... > > s/dispathed/dispatched/ > > s/irq/IRQ/ in the summary and all the English text below. Thanks for your review and sorry for the mismatch, I will fix that in next version. > > On Wed, Dec 20, 2017 at 10:52:14AM +0800, honghui.zhang at mediatek.com wrote: > > From: Honghui Zhang <honghui.zhang@mediatek.com> > > > > There maybe a same irq reentry scenario after irq received in current > > irq handle flow: > > EP device PCIe host driver EP driver > > 1. issue an irq > > 2. received irq > > 3. clear irq status > > 4. dispatch irq > > 5. clear irq source > > The irq status was not successfully cleared at step 2 since the irq > > source was not cleared yet. So the PCIe host driver may receive the > > same irq after step 5. Then there's an irq reentry occurred. > > Even worse, if the reentry irq was not an irq that EP driver expected, > > it may not handle the irq. Then we may run into the dead loop from > > By "dead loop" I assume you mean "infinite loop"? I don't think it's > a deadlock since nothing is waiting. > Yes, it should be "infinite loop", I will update the commit message in next version. thanks. > > step 2 to step 4. > > Clear the irq status after irq have been dispatched to avoid the irq > > reentry. > > > > Signed-off-by: Honghui Zhang <honghui.zhang@mediatek.com> > > --- > > drivers/pci/host/pcie-mediatek.c | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/pci/host/pcie-mediatek.c b/drivers/pci/host/pcie-mediatek.c > > index db93efd..3248771 100644 > > --- a/drivers/pci/host/pcie-mediatek.c > > +++ b/drivers/pci/host/pcie-mediatek.c > > @@ -605,11 +605,11 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) > > > > while ((status = readl(port->base + PCIE_INT_STATUS)) & INTX_MASK) { > > for_each_set_bit_from(bit, &status, PCI_NUM_INTX + INTX_SHIFT) { > > - /* Clear the INTx */ > > - writel(1 << bit, port->base + PCIE_INT_STATUS); > > virq = irq_find_mapping(port->irq_domain, > > bit - INTX_SHIFT); > > generic_handle_irq(virq); > > + /* Clear the INTx */ > > + writel(1 << bit, port->base + PCIE_INT_STATUS); > > } > > } > > > > @@ -619,10 +619,10 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) > > > > while ((imsi_status = readl(port->base + PCIE_IMSI_STATUS))) { > > for_each_set_bit(bit, &imsi_status, MTK_MSI_IRQS_NUM) { > > - /* Clear the MSI */ > > - writel(1 << bit, port->base + PCIE_IMSI_STATUS); > > virq = irq_find_mapping(port->msi_domain, bit); > > generic_handle_irq(virq); > > + /* Clear the MSI */ > > + writel(1 << bit, port->base + PCIE_IMSI_STATUS); > > } > > } > > /* Clear MSI interrupt status */ > > -- > > 2.6.4 > > > > > > _______________________________________________ > > linux-arm-kernel mailing list > > linux-arm-kernel at lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2017-12-21 1:37 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2017-12-20 2:52 [PATCH] PCI: Mediatek: clear irq status after irq dispathed to avoid reentry honghui.zhang at mediatek.com 2017-12-20 3:08 ` Ryder Lee 2017-12-21 0:52 ` Bjorn Helgaas 2017-12-21 1:37 ` Honghui Zhang
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox