linux-kernel - [PATCH v3 1/3] xen/events: Cleanup find

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Message-ID: <20250828003604.8949-2-jason.andryuk@amd.com>
Date: Wed, 27 Aug 2025 20:36:01 -0400
From: Jason Andryuk <jason.andryuk@....com>
To: Juergen Gross <jgross@...e.com>, Stefano Stabellini
	<sstabellini@...nel.org>, Oleksandr Tyshchenko
	<oleksandr_tyshchenko@...m.com>, Konrad Rzeszutek Wilk
	<konrad.wilk@...cle.com>, Olaf Hering <olaf@...fle.de>
CC: Jason Andryuk <jason.andryuk@....com>, <stable@...r.kernel.org>, "Jan
 Beulich" <jbeulich@...e.com>, <xen-devel@...ts.xenproject.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH v3 1/3] xen/events: Cleanup find_virq() return codes

rc is overwritten by the evtchn_status hypercall in each iteration, so
the return value will be whatever the last iteration is.  This could
incorrectly return success even if the event channel was not found.
Change to an explicit -ENOENT for an un-found virq and return 0 on a
successful match.

Fixes: 62cc5fc7b2e0 ("xen/pv-on-hvm kexec: rebind virqs to existing eventchannel ports")
Cc: stable@...r.kernel.org
Signed-off-by: Jason Andryuk <jason.andryuk@....com>
Reviewed-by: Jan Beulich <jbeulich@...e.com>
Reviewed-by: Juergen Gross <jgross@...e.com>
---
v3:
Reduce rc's scope
Add R-b: Jan
Mention false success in commit message
Add Fixes
Cc: stable
Add R-b: Juergen

v2:
New
---
 drivers/xen/events/events_base.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 41309d38f78c..374231d84e4f 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1318,10 +1318,11 @@ static int find_virq(unsigned int virq, unsigned int cpu, evtchn_port_t *evtchn)
 {
 	struct evtchn_status status;
 	evtchn_port_t port;
-	int rc = -ENOENT;
 
 	memset(&status, 0, sizeof(status));
 	for (port = 0; port < xen_evtchn_max_channels(); port++) {
+		int rc;
+
 		status.dom = DOMID_SELF;
 		status.port = port;
 		rc = HYPERVISOR_event_channel_op(EVTCHNOP_status, &status);
@@ -1331,10 +1332,10 @@ static int find_virq(unsigned int virq, unsigned int cpu, evtchn_port_t *evtchn)
 			continue;
 		if (status.u.virq == virq && status.vcpu == xen_vcpu_nr(cpu)) {
 			*evtchn = port;
-			break;
+			return 0;
 		}
 	}
-	return rc;
+	return -ENOENT;
 }
 
 /**
-- 
2.34.1