linux-kernel - Re: [PATCH] mshv: fix SRCU protection in irqfd resampler ack handler

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Message-ID: <aYTP_sgl5fqQoaO8@skinsburskii.localdomain>
Date: Thu, 5 Feb 2026 09:14:38 -0800
From: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
To: lirongqing <lirongqing@...du.com>
Cc: "K . Y . Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
	Long Li <longli@...rosoft.com>, linux-hyperv@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mshv: fix SRCU protection in irqfd resampler ack handler

On Thu, Feb 05, 2026 at 04:40:10AM -0500, lirongqing wrote:
> From: Li RongQing <lirongqing@...du.com>
> 
> Replace hlist_for_each_entry_rcu() with hlist_for_each_entry_srcu()
> in mshv_irqfd_resampler_ack() to correctly handle SRCU-protected
> linked list traversal.
> 
> The function uses SRCU (sleepable RCU) synchronization via
> partition->pt_irq_srcu, but was incorrectly using the RCU variant
> for list iteration. This could lead to race conditions when the
> list is modified concurrently.
> 
> Also add srcu_read_lock_held() assertion as required by
> hlist_for_each_entry_srcu() to ensure we're in the proper
> read-side critical section.
> 

Thank you.

Acked-by: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>

> Signed-off-by: Li RongQing <lirongqing@...du.com>
> ---
>  drivers/hv/mshv_eventfd.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hv/mshv_eventfd.c b/drivers/hv/mshv_eventfd.c
> index 0b75ff1..6d176ed 100644
> --- a/drivers/hv/mshv_eventfd.c
> +++ b/drivers/hv/mshv_eventfd.c
> @@ -87,8 +87,9 @@ static void mshv_irqfd_resampler_ack(struct mshv_irq_ack_notifier *mian)
>  
>  	idx = srcu_read_lock(&partition->pt_irq_srcu);
>  
> -	hlist_for_each_entry_rcu(irqfd, &resampler->rsmplr_irqfd_list,
> -				 irqfd_resampler_hnode) {
> +	hlist_for_each_entry_srcu(irqfd, &resampler->rsmplr_irqfd_list,
> +				 irqfd_resampler_hnode,
> +				 srcu_read_lock_held(&partition->pt_irq_srcu)) {
>  		if (hv_should_clear_interrupt(irqfd->irqfd_lapic_irq.lapic_control.interrupt_type))
>  			hv_call_clear_virtual_interrupt(partition->pt_id);
>  
> -- 
> 2.9.4
>