* Re: [PATCH v2] cxl/events: Return IRQ_NONE when no event is pending
2026-09-12 9:38 [PATCH v2] cxl/events: Return IRQ_NONE when no event is pending Shaikh Kamaluddin
@ 2026-09-15 23:28 ` Jonathan Cameron
2026-09-16 0:38 ` Anisa Su
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: Jonathan Cameron @ 2026-09-15 23:28 UTC (permalink / raw)
To: Shaikh Kamaluddin
Cc: Davidlohr Bueso, Dave Jiang, Alison Schofield, Vishal Verma,
Dan Williams, Ira Weiny, Li Ming, anisa.su887, benjamin.cheatham,
linux-cxl, linux-kernel
On Sat, 12 Sep 2026 15:08:15 +0530
Shaikh Kamaluddin <shaikhkamal2012@gmail.com> wrote:
> CXL event interrupts may share an MSI/MSI-X vector with other event
> logs or device features. Consequently, cxl_event_thread() is registered
> with IRQF_SHARED and must determine whether the event-log facility
> claimed the interrupt.
>
> The handler masks the Device Event Status register to the event logs
> supported by the driver. However, when no supported status bit is set,
> it exits the processing loop and still returns IRQ_HANDLED. This
> incorrectly reports that the interrupt was claimed and prevents the
> generic spurious-interrupt detector from accounting it as unhandled.
>
> Track whether the CXL event handler claimed the interrupt and return
> IRQ_NONE when no supported event is detected. If no handler sharing the
> vector claims a sustained interrupt storm, the generic spurious-
> interrupt detector can eventually identify and disable the affected
> IRQ.
>
> Signed-off-by: Shaikh Kamaluddin <shaikhkamal2012@gmail.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2] cxl/events: Return IRQ_NONE when no event is pending
2026-09-12 9:38 [PATCH v2] cxl/events: Return IRQ_NONE when no event is pending Shaikh Kamaluddin
2026-09-15 23:28 ` Jonathan Cameron
@ 2026-09-16 0:38 ` Anisa Su
2026-09-16 14:30 ` Shaikh Kamaluddin
2026-09-16 12:34 ` Li Ming
2026-09-16 20:49 ` Alison Schofield
3 siblings, 1 reply; 6+ messages in thread
From: Anisa Su @ 2026-09-16 0:38 UTC (permalink / raw)
To: Shaikh Kamaluddin
Cc: Davidlohr Bueso, Jonathan Cameron, Dave Jiang, Alison Schofield,
Vishal Verma, Dan Williams, Ira Weiny, Li Ming, anisa.su887,
benjamin.cheatham, linux-cxl, linux-kernel
On Sat, Sep 12, 2026 at 03:08:15PM +0530, Shaikh Kamaluddin wrote:
> CXL event interrupts may share an MSI/MSI-X vector with other event
> logs or device features. Consequently, cxl_event_thread() is registered
> with IRQF_SHARED and must determine whether the event-log facility
> claimed the interrupt.
>
> The handler masks the Device Event Status register to the event logs
> supported by the driver. However, when no supported status bit is set,
> it exits the processing loop and still returns IRQ_HANDLED. This
> incorrectly reports that the interrupt was claimed and prevents the
> generic spurious-interrupt detector from accounting it as unhandled.
>
> Track whether the CXL event handler claimed the interrupt and return
> IRQ_NONE when no supported event is detected. If no handler sharing the
> vector claims a sustained interrupt storm, the generic spurious-
> interrupt detector can eventually identify and disable the affected
> IRQ.
>
> Signed-off-by: Shaikh Kamaluddin <shaikhkamal2012@gmail.com>
Reviewed-by: Anisa Su <anisa.su@samsung.com>
> ---
> Changes in V2:
> - Emphasize that returning IRQ_NONE enables generic spurious-interrupt
> detection and drop the Fixes tag. (Jonathan Cameron)
> - Check whether the event interrupt is already disabled by Anisa Su's
> patch; no code changes were needed. (Ben Cheatham)
One thing I want to correct: The change requested was to say a
spurious IRQ will eventually be disabled in the commit message, not
check whether the event interrupts is already disabled...
See https://lore.kernel.org/linux-cxl/aqLZP3ORYzCLfSgR@acer-nitro-anv15-41/T/#m32c74ebf05eee9a3ee49c57dd24848db29919031
I do see that it's been added to the commit message though, so no need
to do anything.
Thanks,
Anisa
> - Rebase onto v7.3-rc2; no code changes.
>
> drivers/cxl/pci.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index c7c91e8dc51d..8b560cae91f2 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -515,6 +515,7 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
> struct cxl_dev_id *dev_id = id;
> struct cxl_dev_state *cxlds = dev_id->cxlds;
> struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
> + bool handled = false;
> u32 status;
>
> do {
> @@ -527,11 +528,13 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
> status &= CXLDEV_EVENT_STATUS_ALL;
> if (!status)
> break;
> +
> + handled = true;
> cxl_mem_get_event_records(mds, status);
> cond_resched();
> } while (status);
>
> - return IRQ_HANDLED;
> + return handled ? IRQ_HANDLED : IRQ_NONE;
> }
>
> static int cxl_event_req_irq(struct cxl_dev_state *cxlds, u8 setting)
>
> base-commit: df2908090cda368b01ff43709f51890076c56157
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2] cxl/events: Return IRQ_NONE when no event is pending
2026-09-16 0:38 ` Anisa Su
@ 2026-09-16 14:30 ` Shaikh Kamaluddin
0 siblings, 0 replies; 6+ messages in thread
From: Shaikh Kamaluddin @ 2026-09-16 14:30 UTC (permalink / raw)
To: Anisa Su
Cc: Davidlohr Bueso, Jonathan Cameron, Dave Jiang, Alison Schofield,
Vishal Verma, Dan Williams, Ira Weiny, Li Ming,
benjamin.cheatham, linux-cxl, linux-kernel
On Wed, Sep 16, 2026 at 09:38:37AM +0900, Anisa Su wrote:
> On Sat, Sep 12, 2026 at 03:08:15PM +0530, Shaikh Kamaluddin wrote:
> > CXL event interrupts may share an MSI/MSI-X vector with other event
> > logs or device features. Consequently, cxl_event_thread() is registered
> > with IRQF_SHARED and must determine whether the event-log facility
> > claimed the interrupt.
> >
> > The handler masks the Device Event Status register to the event logs
> > supported by the driver. However, when no supported status bit is set,
> > it exits the processing loop and still returns IRQ_HANDLED. This
> > incorrectly reports that the interrupt was claimed and prevents the
> > generic spurious-interrupt detector from accounting it as unhandled.
> >
> > Track whether the CXL event handler claimed the interrupt and return
> > IRQ_NONE when no supported event is detected. If no handler sharing the
> > vector claims a sustained interrupt storm, the generic spurious-
> > interrupt detector can eventually identify and disable the affected
> > IRQ.
> >
> > Signed-off-by: Shaikh Kamaluddin <shaikhkamal2012@gmail.com>
> Reviewed-by: Anisa Su <anisa.su@samsung.com>
> > ---
> > Changes in V2:
> > - Emphasize that returning IRQ_NONE enables generic spurious-interrupt
> > detection and drop the Fixes tag. (Jonathan Cameron)
> > - Check whether the event interrupt is already disabled by Anisa Su's
> > patch; no code changes were needed. (Ben Cheatham)
>
> One thing I want to correct: The change requested was to say a
> spurious IRQ will eventually be disabled in the commit message, not
> check whether the event interrupts is already disabled...
> See https://lore.kernel.org/linux-cxl/aqLZP3ORYzCLfSgR@acer-nitro-anv15-41/T/#m32c74ebf05eee9a3ee49c57dd24848db29919031
> I do see that it's been added to the commit message though, so no need
> to do anything.
>
Hi Anisa,
I got your point, yes commit message already covered this.
Thanks,
Shaikh
> Thanks,
> Anisa
> > - Rebase onto v7.3-rc2; no code changes.
> >
> > drivers/cxl/pci.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> > index c7c91e8dc51d..8b560cae91f2 100644
> > --- a/drivers/cxl/pci.c
> > +++ b/drivers/cxl/pci.c
> > @@ -515,6 +515,7 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
> > struct cxl_dev_id *dev_id = id;
> > struct cxl_dev_state *cxlds = dev_id->cxlds;
> > struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
> > + bool handled = false;
> > u32 status;
> >
> > do {
> > @@ -527,11 +528,13 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
> > status &= CXLDEV_EVENT_STATUS_ALL;
> > if (!status)
> > break;
> > +
> > + handled = true;
> > cxl_mem_get_event_records(mds, status);
> > cond_resched();
> > } while (status);
> >
> > - return IRQ_HANDLED;
> > + return handled ? IRQ_HANDLED : IRQ_NONE;
> > }
> >
> > static int cxl_event_req_irq(struct cxl_dev_state *cxlds, u8 setting)
> >
> > base-commit: df2908090cda368b01ff43709f51890076c56157
> > --
> > 2.43.0
> >
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] cxl/events: Return IRQ_NONE when no event is pending
2026-09-12 9:38 [PATCH v2] cxl/events: Return IRQ_NONE when no event is pending Shaikh Kamaluddin
2026-09-15 23:28 ` Jonathan Cameron
2026-09-16 0:38 ` Anisa Su
@ 2026-09-16 12:34 ` Li Ming
2026-09-16 20:49 ` Alison Schofield
3 siblings, 0 replies; 6+ messages in thread
From: Li Ming @ 2026-09-16 12:34 UTC (permalink / raw)
To: Shaikh Kamaluddin, Davidlohr Bueso, Jonathan Cameron, Dave Jiang,
Alison Schofield, Vishal Verma, Dan Williams, Ira Weiny
Cc: anisa.su887, benjamin.cheatham, linux-cxl, linux-kernel
On 9/12/2026 5:38 PM, Shaikh Kamaluddin wrote:
> CXL event interrupts may share an MSI/MSI-X vector with other event
> logs or device features. Consequently, cxl_event_thread() is registered
> with IRQF_SHARED and must determine whether the event-log facility
> claimed the interrupt.
>
> The handler masks the Device Event Status register to the event logs
> supported by the driver. However, when no supported status bit is set,
> it exits the processing loop and still returns IRQ_HANDLED. This
> incorrectly reports that the interrupt was claimed and prevents the
> generic spurious-interrupt detector from accounting it as unhandled.
>
> Track whether the CXL event handler claimed the interrupt and return
> IRQ_NONE when no supported event is detected. If no handler sharing the
> vector claims a sustained interrupt storm, the generic spurious-
> interrupt detector can eventually identify and disable the affected
> IRQ.
>
> Signed-off-by: Shaikh Kamaluddin <shaikhkamal2012@gmail.com>
Reviewed-by: Li Ming <ming.li@zohomail.com>
> ---
> Changes in V2:
> - Emphasize that returning IRQ_NONE enables generic spurious-interrupt
> detection and drop the Fixes tag. (Jonathan Cameron)
> - Check whether the event interrupt is already disabled by Anisa Su's
> patch; no code changes were needed. (Ben Cheatham)
> - Rebase onto v7.3-rc2; no code changes.
>
> drivers/cxl/pci.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index c7c91e8dc51d..8b560cae91f2 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -515,6 +515,7 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
> struct cxl_dev_id *dev_id = id;
> struct cxl_dev_state *cxlds = dev_id->cxlds;
> struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
> + bool handled = false;
> u32 status;
>
> do {
> @@ -527,11 +528,13 @@ static irqreturn_t cxl_event_thread(int irq, void *id)
> status &= CXLDEV_EVENT_STATUS_ALL;
> if (!status)
> break;
> +
> + handled = true;
> cxl_mem_get_event_records(mds, status);
> cond_resched();
> } while (status);
>
> - return IRQ_HANDLED;
> + return handled ? IRQ_HANDLED : IRQ_NONE;
> }
>
> static int cxl_event_req_irq(struct cxl_dev_state *cxlds, u8 setting)
>
> base-commit: df2908090cda368b01ff43709f51890076c56157
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2] cxl/events: Return IRQ_NONE when no event is pending
2026-09-12 9:38 [PATCH v2] cxl/events: Return IRQ_NONE when no event is pending Shaikh Kamaluddin
` (2 preceding siblings ...)
2026-09-16 12:34 ` Li Ming
@ 2026-09-16 20:49 ` Alison Schofield
3 siblings, 0 replies; 6+ messages in thread
From: Alison Schofield @ 2026-09-16 20:49 UTC (permalink / raw)
To: Shaikh Kamaluddin
Cc: Davidlohr Bueso, Jonathan Cameron, Dave Jiang, Vishal Verma,
Dan Williams, Ira Weiny, Li Ming, anisa.su887, benjamin.cheatham,
linux-cxl, linux-kernel
On Sat, Sep 12, 2026 at 03:08:15PM +0530, Shaikh Kamaluddin wrote:
> CXL event interrupts may share an MSI/MSI-X vector with other event
> logs or device features. Consequently, cxl_event_thread() is registered
> with IRQF_SHARED and must determine whether the event-log facility
> claimed the interrupt.
>
> The handler masks the Device Event Status register to the event logs
> supported by the driver. However, when no supported status bit is set,
> it exits the processing loop and still returns IRQ_HANDLED. This
> incorrectly reports that the interrupt was claimed and prevents the
> generic spurious-interrupt detector from accounting it as unhandled.
>
> Track whether the CXL event handler claimed the interrupt and return
> IRQ_NONE when no supported event is detected. If no handler sharing the
> vector claims a sustained interrupt storm, the generic spurious-
> interrupt detector can eventually identify and disable the affected
> IRQ.
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
^ permalink raw reply [flat|nested] 6+ messages in thread