From: Thomas Gleixner <tglx@linutronix.de>
To: Luigi Rizzo <lrizzo@google.com>, Marc Zyngier <maz@kernel.org>,
Luigi Rizzo <rizzo.unipi@gmail.com>,
Paolo Abeni <pabeni@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Sean Christopherson <seanjc@google.com>,
Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
Bjorn Helgaas <bhelgaas@google.com>,
Willem de Bruijn <willemb@google.com>,
Luigi Rizzo <lrizzo@google.com>
Subject: Re: [PATCH 2/6] genirq: soft_moderation: add base files, procfs hooks
Date: Thu, 13 Nov 2025 11:24:58 +0100 [thread overview]
Message-ID: <87h5uycjr9.ffs@tglx> (raw)
In-Reply-To: <87346ie0vs.ffs@tglx>
On Thu, Nov 13 2025 at 10:29, Thomas Gleixner wrote:
> On Wed, Nov 12 2025 at 19:24, Luigi Rizzo wrote:
>> +static void set_moderation_mode(struct irq_desc *desc, bool mode)
>> +{
>> + if (desc) {
>
> Why would desc be NULL?
>
>> + struct irq_chip *chip = desc->irq_data.chip;
>> +
>> + /* Make sure this is msi and we can run enable_irq from irq context */
>> + mode &= desc->handle_irq == handle_edge_irq && chip && chip->irq_bus_lock == NULL &&
>> + chip->irq_bus_sync_unlock == NULL;
Q: How does this make sure that it is MSI?
A: Not at all
Q: How is this protected against concurrent modification?
A: Not at all
>> + if (mode != desc->moderation_mode)
>> + desc->moderation_mode = mode;
This conditional is truly making a difference.
Thanks
tglx
next prev parent reply other threads:[~2025-11-13 10:25 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-12 19:24 [PATCH 0/6] platform wide software interrupt moderation Luigi Rizzo
2025-11-12 19:24 ` [PATCH 1/6] genirq: platform wide interrupt moderation: Documentation, Kconfig, irq_desc Luigi Rizzo
2025-11-13 8:17 ` Thomas Gleixner
2025-11-13 9:44 ` Thomas Gleixner
2025-11-13 13:25 ` Marc Zyngier
2025-11-13 13:33 ` Luigi Rizzo
2025-11-13 14:42 ` Marc Zyngier
2025-11-13 14:55 ` Luigi Rizzo
2025-11-13 19:02 ` Marc Zyngier
2025-11-12 19:24 ` [PATCH 2/6] genirq: soft_moderation: add base files, procfs hooks Luigi Rizzo
2025-11-13 9:29 ` Thomas Gleixner
2025-11-13 10:24 ` Thomas Gleixner [this message]
2025-11-13 22:42 ` Luigi Rizzo
2025-11-13 22:32 ` Luigi Rizzo
2025-11-13 9:40 ` Thomas Gleixner
2025-11-12 19:24 ` [PATCH 3/6] genirq: soft_moderation: activate hooks in handle_irq_event() Luigi Rizzo
2025-11-13 9:45 ` Thomas Gleixner
2025-11-14 8:27 ` Luigi Rizzo
2025-11-12 19:24 ` [PATCH 4/6] genirq: soft_moderation: implement adaptive moderation Luigi Rizzo
2025-11-13 10:15 ` Thomas Gleixner
2025-11-12 19:24 ` [PATCH 5/6] x86/irq: soft_moderation: add support for posted_msi (intel) Luigi Rizzo
2025-11-12 19:24 ` [PATCH 6/6] genirq: soft_moderation: implement per-driver defaults (nvme and vfio) Luigi Rizzo
2025-11-13 10:18 ` Thomas Gleixner
2025-11-13 10:42 ` Luigi Rizzo
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