> -----Original Message----- > From: Thomas Gleixner [mailto:tglx@xxxxxxxxxxxxx] > Sent: Tuesday, February 25, 2014 11:10 AM > To: KY Srinivasan > Cc: LKML; Ingo Molnar; Peter Zijlstra; x86; Greg Kroah-Hartman; linuxdrivers > Subject: RE: [patch 25/26] x86: hyperv: Cleanup the irq mess > > On Tue, 25 Feb 2014, KY Srinivasan wrote: > > > -----Original Message----- > > > From: Thomas Gleixner [mailto:tglx@xxxxxxxxxxxxx] > > > Sent: Sunday, February 23, 2014 1:40 PM > > > To: LKML > > > Cc: Ingo Molnar; Peter Zijlstra; x86; KY Srinivasan; Greg > > > Kroah-Hartman; linuxdrivers > > > Subject: [patch 25/26] x86: hyperv: Cleanup the irq mess > > > > > > The vmbus/hyperv interrupt handling is another complete trainwreck > > > and probably the worst of all currently in tree. > > > > > > If CONFIG_HYPERV=y then the interrupt delivery to the vmbus happens > > > via the direct HYPERVISOR_CALLBACK_VECTOR. So far so good, but: > > > > > > The driver requests first a normal device interrupt. The only reason > > > to do so is to increment the interrupt stats of that device > > > interrupt. > > > > > > We have proper accounting mechanisms for direct vectors, but of > > > course it's too much effort to add that 5 lines of code. > > > > > > Aside of that the alloc_intr_gate() is not protected against > > > reallocation which makes module reload impossible. > > > > > > If CONFIG_HYPERV=n then the vmbus request a regular device interrupt > > > via > > > request_irq() and installs it's own private flow handler. Of course > > > this lacks any explanation why it can't use the standard flow > > > handler or the existing handle_percpu_irq handler. > > > > > > Solution to the problem is simple to rip out the whole mess and > > > implement it correctly. > > Thomas, > > > > Thank you for cleaning up this code. When CONFIG_HYPERV== n, none of > > the VMBUS code is active. The special case can go away as you have > > noted. > > So, if CONFIG_HYPERV=n then you do not need the request_irq() fallback at > all, right? Somehow I missed the HYPERV dependency of the VMBUS stuff > > That makes stuff even simpler as we can get rid of those extra cases including > the extra flow handler. > > New patch below. Thanks Thomas. Acked-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > > Thanks, > > tglx > --- > > arch/x86/include/asm/mshyperv.h | 4 +- > arch/x86/kernel/cpu/mshyperv.c | 78 ++++++++++++++++++++------------- > ------- > drivers/hv/vmbus_drv.c | 39 ++------------------ > 3 files changed, 47 insertions(+), 74 deletions(-) > > Index: tip/arch/x86/include/asm/mshyperv.h > ========================================================== > ========= > --- tip.orig/arch/x86/include/asm/mshyperv.h > +++ tip/arch/x86/include/asm/mshyperv.h > @@ -2,6 +2,7 @@ > #define _ASM_X86_MSHYPER_H > > #include <linux/types.h> > +#include <linux/interrupt.h> > #include <asm/hyperv.h> > > struct ms_hyperv_info { > @@ -16,6 +17,7 @@ void hyperv_callback_vector(void); #define > trace_hyperv_callback_vector hyperv_callback_vector #endif void > hyperv_vector_handler(struct pt_regs *regs); -void > hv_register_vmbus_handler(int irq, irq_handler_t handler); > +int hv_setup_vmbus_irq(int irq, irq_handler_t handler, void *dev_id); > +void hv_remove_vmbus_irq(int irq, void *dev_id); > > #endif > Index: tip/arch/x86/kernel/cpu/mshyperv.c > ========================================================== > ========= > --- tip.orig/arch/x86/kernel/cpu/mshyperv.c > +++ tip/arch/x86/kernel/cpu/mshyperv.c > @@ -17,6 +17,7 @@ > #include <linux/hardirq.h> > #include <linux/efi.h> > #include <linux/interrupt.h> > +#include <linux/irq.h> > #include <asm/processor.h> > #include <asm/hypervisor.h> > #include <asm/hyperv.h> > @@ -30,6 +31,45 @@ > struct ms_hyperv_info ms_hyperv; > EXPORT_SYMBOL_GPL(ms_hyperv); > > +#ifdef CONFIG_HYPERV > +static irq_handler_t *vmbus_handler; > + > +void hyperv_vector_handler(struct pt_regs *regs) { > + struct pt_regs *old_regs = set_irq_regs(regs); > + > + irq_enter(); > + exit_idle(); > + > + inc_irq_stat(irq_hv_callback_count); > + if (vmbus_handler) > + vmbus_handler(); > + > + irq_exit(); > + set_irq_regs(old_regs); > +} > + > +int hv_setup_vmbus_irq(int irq, irq_handler_t *handler, void *dev_id) { > + vmbus_handler = handler; > + /* > + * Setup the IDT for hypervisor callback. Prevent reallocation > + * at module reload. > + */ > + if (!test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors)) > + alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, > + hyperv_callback_vector); > +} > + > +void hv_remove_vmbus_irq(unsigned int irq, void *dev_id) { > + /* We have no way to deallocate the interrupt gate */ > + vmbus_handler = NULL; > +} > +EXPORT_SYMBOL_GPL(hv_setup_vmbus_irq); > +EXPORT_SYMBOL_GPL(hv_remove_vmbus_irq); > +#endif > + > static uint32_t __init ms_hyperv_platform(void) { > u32 eax; > @@ -113,41 +153,3 @@ const __refconst struct hypervisor_x86 x > .init_platform = ms_hyperv_init_platform, > }; > EXPORT_SYMBOL(x86_hyper_ms_hyperv); > - > -#if IS_ENABLED(CONFIG_HYPERV) > -static int vmbus_irq = -1; > -static irq_handler_t vmbus_isr; > - > -void hv_register_vmbus_handler(int irq, irq_handler_t handler) -{ > - /* > - * Setup the IDT for hypervisor callback. > - */ > - alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, > hyperv_callback_vector); > - > - vmbus_irq = irq; > - vmbus_isr = handler; > -} > - > -void hyperv_vector_handler(struct pt_regs *regs) -{ > - struct pt_regs *old_regs = set_irq_regs(regs); > - struct irq_desc *desc; > - > - irq_enter(); > - exit_idle(); > - > - desc = irq_to_desc(vmbus_irq); > - > - if (desc) > - generic_handle_irq_desc(vmbus_irq, desc); > - > - irq_exit(); > - set_irq_regs(old_regs); > -} > -#else > -void hv_register_vmbus_handler(int irq, irq_handler_t handler) -{ -} -#endif > -EXPORT_SYMBOL_GPL(hv_register_vmbus_handler); > Index: tip/drivers/hv/vmbus_drv.c > ========================================================== > ========= > --- tip.orig/drivers/hv/vmbus_drv.c > +++ tip/drivers/hv/vmbus_drv.c > @@ -25,7 +25,6 @@ > #include <linux/init.h> > #include <linux/module.h> > #include <linux/device.h> > -#include <linux/irq.h> > #include <linux/interrupt.h> > #include <linux/sysctl.h> > #include <linux/slab.h> > @@ -558,9 +557,6 @@ static struct bus_type hv_bus = { > .dev_groups = vmbus_groups, > }; > > -static const char *driver_name = "hyperv"; > - > - > struct onmessage_work_context { > struct work_struct work; > struct hv_message msg; > @@ -677,19 +673,6 @@ static irqreturn_t vmbus_isr(int irq, vo } > > /* > - * vmbus interrupt flow handler: > - * vmbus interrupts can concurrently occur on multiple CPUs and > - * can be handled concurrently. > - */ > - > -static void vmbus_flow_handler(unsigned int irq, struct irq_desc *desc) -{ > - kstat_incr_irqs_this_cpu(irq, desc); > - > - desc->action->handler(irq, desc->action->dev_id); > -} > - > -/* > * vmbus_bus_init -Main vmbus driver initialization routine. > * > * Here, we > @@ -715,26 +698,13 @@ static int vmbus_bus_init(int irq) > if (ret) > goto err_cleanup; > > - ret = request_irq(irq, vmbus_isr, 0, driver_name, hv_acpi_dev); > + ret = hv_setup_vmbus_irq(irq, vmbus_isr, hv_acpi_dev); > > if (ret != 0) { > - pr_err("Unable to request IRQ %d\n", > - irq); > + pr_err("Unable to request IRQ %d\n", irq); > goto err_unregister; > } > > - /* > - * Vmbus interrupts can be handled concurrently on > - * different CPUs. Establish an appropriate interrupt flow > - * handler that can support this model. > - */ > - irq_set_handler(irq, vmbus_flow_handler); > - > - /* > - * Register our interrupt handler. > - */ > - hv_register_vmbus_handler(irq, vmbus_isr); > - > ret = hv_synic_alloc(); > if (ret) > goto err_alloc; > @@ -753,7 +723,7 @@ static int vmbus_bus_init(int irq) > > err_alloc: > hv_synic_free(); > - free_irq(irq, hv_acpi_dev); > + hv_remove_vmbus_irq(irq, hv_acpi_dev); > > err_unregister: > bus_unregister(&hv_bus); > @@ -978,8 +948,7 @@ cleanup: > > static void __exit vmbus_exit(void) > { > - > - free_irq(irq, hv_acpi_dev); > + hv_remove_vmbus_irq(irq, hv_acpi_dev); > vmbus_free_channels(); > bus_unregister(&hv_bus); > hv_cleanup(); > > > > > > _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
