[PATCH 1/1] irq: Maintain user set affinity - Kernel

This is a discussion on [PATCH 1/1] irq: Maintain user set affinity - Kernel ; From 819ad3ed4660f4238e053728a8b5aa93d22b13d7 Mon Sep 17 00:00:00 2001 From: Kumar Gala Date: Tue, 4 Nov 2008 10:13:53 -0600 Subject: [PATCH 1/1] irq: Maintain user set affinity This addresses a regression in that if a user specified an affinity for an interrupt ...

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Thread: [PATCH 1/1] irq: Maintain user set affinity

  1. [PATCH 1/1] irq: Maintain user set affinity

    From 819ad3ed4660f4238e053728a8b5aa93d22b13d7 Mon Sep 17 00:00:00 2001
    From: Kumar Gala
    Date: Tue, 4 Nov 2008 10:13:53 -0600
    Subject: [PATCH 1/1] irq: Maintain user set affinity

    This addresses a regression in that if a user specified an affinity
    for an interrupt that affinity information would get reset between
    a request_irq(), free_irq() and request_irq() for the same irq.

    On example of this is bringing up an ethernet interface, taking
    it down and bringing it back up again.

    Instead of always using the irq_default_affinity we use the
    previous setting of the IRQs affinity with the assumption that
    at boot the IRQs affinity will be set to irq_default_affinity.

    Signed-off-by: Kumar Gala
    ---
    kernel/irq/manage.c | 7 +++++--
    1 files changed, 5 insertions(+), 2 deletions(-)

    diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
    index c498a1b..ea7d11b 100644
    --- a/kernel/irq/manage.c
    +++ b/kernel/irq/manage.c
    @@ -115,9 +115,12 @@ int irq_select_affinity(unsigned int irq)
    if (!irq_can_set_affinity(irq))
    return 0;

    - cpus_and(mask, cpu_online_map, irq_default_affinity);
    -
    desc = irq_to_desc(irq);
    +
    + mask = desc->affinity;
    +
    + cpus_and(mask, cpu_online_map, mask);
    +
    desc->affinity = mask;
    desc->chip->set_affinity(irq, mask);

    --
    1.5.5.1

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  2. Re: [PATCH 1/1] irq: Maintain user set affinity

    On Tue, 4 Nov 2008 10:31:05 -0600 (CST)
    Kumar Gala wrote:

    > >From 819ad3ed4660f4238e053728a8b5aa93d22b13d7 Mon Sep 17 00:00:00 2001

    > From: Kumar Gala
    > Date: Tue, 4 Nov 2008 10:13:53 -0600
    > Subject: [PATCH 1/1] irq: Maintain user set affinity
    >
    > This addresses a regression in that if a user specified an affinity
    > for an interrupt that affinity information would get reset between
    > a request_irq(), free_irq() and request_irq() for the same irq.
    >
    > On example of this is bringing up an ethernet interface, taking
    > it down and bringing it back up again.
    >
    > Instead of always using the irq_default_affinity we use the
    > previous setting of the IRQs affinity with the assumption that
    > at boot the IRQs affinity will be set to irq_default_affinity.
    >
    > Signed-off-by: Kumar Gala
    > ---
    > kernel/irq/manage.c | 7 +++++--
    > 1 files changed, 5 insertions(+), 2 deletions(-)
    >
    > diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
    > index c498a1b..ea7d11b 100644
    > --- a/kernel/irq/manage.c
    > +++ b/kernel/irq/manage.c
    > @@ -115,9 +115,12 @@ int irq_select_affinity(unsigned int irq)
    > if (!irq_can_set_affinity(irq))
    > return 0;
    >
    > - cpus_and(mask, cpu_online_map, irq_default_affinity);
    > -
    > desc = irq_to_desc(irq);
    > +
    > + mask = desc->affinity;
    > +
    > + cpus_and(mask, cpu_online_map, mask);
    > +
    > desc->affinity = mask;
    > desc->chip->set_affinity(irq, mask);
    >


    Are you able to identify when this regression occurred? It isn't
    immediately obvious to me.

    If the regression is present in 2.6.27 or earlier, do you think we
    should backport the fix? If so, a different patch would be needed due
    to the presence of

    commit 08678b0841267c1d00d771fe01548d86043d065e
    Author: Yinghai Lu
    Date: Tue Aug 19 20:50:05 2008 -0700

    generic: sparse irqs: use irq_desc() together with dyn_array, instead of irq_desc[]

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  3. Re: [PATCH 1/1] irq: Maintain user set affinity


    On Nov 6, 2008, at 3:35 PM, Andrew Morton wrote:

    > On Tue, 4 Nov 2008 10:31:05 -0600 (CST)
    > Kumar Gala wrote:
    >
    >>> From 819ad3ed4660f4238e053728a8b5aa93d22b13d7 Mon Sep 17 00:00:00
    >>> 2001

    >> From: Kumar Gala
    >> Date: Tue, 4 Nov 2008 10:13:53 -0600
    >> Subject: [PATCH 1/1] irq: Maintain user set affinity
    >>
    >> This addresses a regression in that if a user specified an affinity
    >> for an interrupt that affinity information would get reset between
    >> a request_irq(), free_irq() and request_irq() for the same irq.
    >>
    >> On example of this is bringing up an ethernet interface, taking
    >> it down and bringing it back up again.
    >>
    >> Instead of always using the irq_default_affinity we use the
    >> previous setting of the IRQs affinity with the assumption that
    >> at boot the IRQs affinity will be set to irq_default_affinity.
    >>
    >> Signed-off-by: Kumar Gala
    >> ---
    >> kernel/irq/manage.c | 7 +++++--
    >> 1 files changed, 5 insertions(+), 2 deletions(-)
    >>
    >> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
    >> index c498a1b..ea7d11b 100644
    >> --- a/kernel/irq/manage.c
    >> +++ b/kernel/irq/manage.c
    >> @@ -115,9 +115,12 @@ int irq_select_affinity(unsigned int irq)
    >> if (!irq_can_set_affinity(irq))
    >> return 0;
    >>
    >> - cpus_and(mask, cpu_online_map, irq_default_affinity);
    >> -
    >> desc = irq_to_desc(irq);
    >> +
    >> + mask = desc->affinity;
    >> +
    >> + cpus_and(mask, cpu_online_map, mask);
    >> +
    >> desc->affinity = mask;
    >> desc->chip->set_affinity(irq, mask);
    >>

    >
    > Are you able to identify when this regression occurred? It isn't
    > immediately obvious to me.
    >
    > If the regression is present in 2.6.27 or earlier, do you think we
    > should backport the fix? If so, a different patch would be needed due
    > to the presence of
    >
    > commit 08678b0841267c1d00d771fe01548d86043d065e
    > Author: Yinghai Lu
    > Date: Tue Aug 19 20:50:05 2008 -0700
    >
    > generic: sparse irqs: use irq_desc() together with dyn_array,
    > instead of irq_desc[]


    It didn't creep in during 2.6.27. I will back port a patch to
    2.6.27. Thomas has provided me a better patch that handles a few
    critical issues that mine doesn't. I'll be testing it this evening
    and will backport to 2.6.27 if it works out.

    - k
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  4. Re: [PATCH 1/1] irq: Maintain user set affinity

    On Tue, Nov 4, 2008 at 8:31 AM, Kumar Gala wrote:
    > From 819ad3ed4660f4238e053728a8b5aa93d22b13d7 Mon Sep 17 00:00:00 2001
    > From: Kumar Gala
    > Date: Tue, 4 Nov 2008 10:13:53 -0600
    > Subject: [PATCH 1/1] irq: Maintain user set affinity
    >
    > This addresses a regression in that if a user specified an affinity
    > for an interrupt that affinity information would get reset between
    > a request_irq(), free_irq() and request_irq() for the same irq.
    >
    > On example of this is bringing up an ethernet interface, taking
    > it down and bringing it back up again.
    >
    > Instead of always using the irq_default_affinity we use the
    > previous setting of the IRQs affinity with the assumption that
    > at boot the IRQs affinity will be set to irq_default_affinity.


    why ?, the default_affinity is expected behavior...

    for example: when MSI is used, second driver could get same irq if
    first driver is unloaded.

    YH
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  5. Re: [PATCH 1/1] irq: Maintain user set affinity

    On Sat, 2008-11-08 at 14:12 -0800, Yinghai Lu wrote:
    > On Tue, Nov 4, 2008 at 8:31 AM, Kumar Gala wrote:
    > > From 819ad3ed4660f4238e053728a8b5aa93d22b13d7 Mon Sep 17 00:00:00 2001
    > > From: Kumar Gala
    > > Date: Tue, 4 Nov 2008 10:13:53 -0600
    > > Subject: [PATCH 1/1] irq: Maintain user set affinity
    > >
    > > This addresses a regression in that if a user specified an affinity
    > > for an interrupt that affinity information would get reset between
    > > a request_irq(), free_irq() and request_irq() for the same irq.
    > >
    > > On example of this is bringing up an ethernet interface, taking
    > > it down and bringing it back up again.
    > >
    > > Instead of always using the irq_default_affinity we use the
    > > previous setting of the IRQs affinity with the assumption that
    > > at boot the IRQs affinity will be set to irq_default_affinity.

    >
    > why ?, the default_affinity is expected behavior...
    >
    > for example: when MSI is used, second driver could get same irq if
    > first driver is unloaded.


    The default affinity should be set when the irq is allocated / assigned
    to a device, not when it's requested.

    Ben.


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  6. Re: [PATCH 1/1] irq: Maintain user set affinity

    On Thu, Nov 6, 2008 at 1:35 PM, Andrew Morton wrote:
    > On Tue, 4 Nov 2008 10:31:05 -0600 (CST)
    > Kumar Gala wrote:
    >
    >> >From 819ad3ed4660f4238e053728a8b5aa93d22b13d7 Mon Sep 17 00:00:00 2001

    >> From: Kumar Gala
    >> Date: Tue, 4 Nov 2008 10:13:53 -0600
    >> Subject: [PATCH 1/1] irq: Maintain user set affinity
    >>
    >> This addresses a regression in that if a user specified an affinity
    >> for an interrupt that affinity information would get reset between
    >> a request_irq(), free_irq() and request_irq() for the same irq.
    >>

    ....
    >
    > Are you able to identify when this regression occurred? It isn't
    > immediately obvious to me.
    >
    > If the regression is present in 2.6.27 or earlier, do you think we
    > should backport the fix? If so, a different patch would be needed due
    > to the presence of


    it seems that is not a regression...

    YH
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  7. Re: [PATCH 1/1] irq: Maintain user set affinity

    On Sat, Nov 8, 2008 at 2:17 PM, Benjamin Herrenschmidt
    wrote:
    > On Sat, 2008-11-08 at 14:12 -0800, Yinghai Lu wrote:
    >> On Tue, Nov 4, 2008 at 8:31 AM, Kumar Gala wrote:
    >> > From 819ad3ed4660f4238e053728a8b5aa93d22b13d7 Mon Sep 17 00:00:00 2001
    >> > From: Kumar Gala
    >> > Date: Tue, 4 Nov 2008 10:13:53 -0600
    >> > Subject: [PATCH 1/1] irq: Maintain user set affinity
    >> >
    >> > This addresses a regression in that if a user specified an affinity
    >> > for an interrupt that affinity information would get reset between
    >> > a request_irq(), free_irq() and request_irq() for the same irq.
    >> >
    >> > On example of this is bringing up an ethernet interface, taking
    >> > it down and bringing it back up again.
    >> >
    >> > Instead of always using the irq_default_affinity we use the
    >> > previous setting of the IRQs affinity with the assumption that
    >> > at boot the IRQs affinity will be set to irq_default_affinity.

    >>
    >> why ?, the default_affinity is expected behavior...
    >>
    >> for example: when MSI is used, second driver could get same irq if
    >> first driver is unloaded.

    >
    > The default affinity should be set when the irq is allocated / assigned
    > to a device, not when it's requested.


    ok, you are right.

    for MSI, affinity is set two times.

    also in dynamic_irq_init is setting with
    #ifdef CONFIG_SMP
    cpus_setall(desc->affinity);
    #endif

    it seems should use irq_default_affinity instead of CPU_MASK_ALL directly there.

    YH
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  8. Re: [PATCH 1/1] irq: Maintain user set affinity


    > for MSI, affinity is set two times.
    >
    > also in dynamic_irq_init is setting with
    > #ifdef CONFIG_SMP
    > cpus_setall(desc->affinity);
    > #endif
    >
    > it seems should use irq_default_affinity instead of CPU_MASK_ALL directly there.


    That sounds more like it.

    Cheers,
    Ben.


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