[PATCH 1/4] PCI: endpoint: pci-epf-vntb: Fix MSI doorbell IRQ unwind

[Koichiro Den]

epf_ntb_db_bar_init_msi_doorbell() requests ntb->db_count doorbell IRQs
and then performs additional MSI doorbell setup that may still fail.
The error path unwinds the requested IRQs, but it uses a loop variable
that is reused later in the function. When a later step fails, the
unwind can run with an unexpected index value and leave some IRQs
requested.

Track the number of successfully requested IRQs separately and use that
counter for the unwind so all previously requested IRQs are freed on
failure.

Fixes: dc693d606644 ("PCI: endpoint: pci-epf-vntb: Add MSI doorbell support")
Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
---
 drivers/pci/endpoint/functions/pci-epf-vntb.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
index 20a400e83439..20efa27325f1 100644
--- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
@@ -523,6 +523,7 @@ static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
 					    enum pci_barno barno)
 {
 	struct pci_epf *epf = ntb->epf;
+	unsigned int req;
 	dma_addr_t low, high;
 	struct msi_msg *msg;
 	size_t sz;
@@ -533,14 +534,14 @@ static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
 	if (ret)
 		return ret;
 
-	for (i = 0; i < ntb->db_count; i++) {
-		ret = request_irq(epf->db_msg[i].virq, epf_ntb_doorbell_handler,
+	for (req = 0; req < ntb->db_count; req++) {
+		ret = request_irq(epf->db_msg[req].virq, epf_ntb_doorbell_handler,
 				  0, "pci_epf_vntb_db", ntb);
 
 		if (ret) {
 			dev_err(&epf->dev,
 				"Failed to request doorbell IRQ: %d\n",
-				epf->db_msg[i].virq);
+				epf->db_msg[req].virq);
 			goto err_free_irq;
 		}
 	}
@@ -598,8 +599,8 @@ static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
 	return 0;
 
 err_free_irq:
-	for (i--; i >= 0; i--)
-		free_irq(epf->db_msg[i].virq, ntb);
+	while (req)
+		free_irq(epf->db_msg[--req].virq, ntb);
 
 	pci_epf_free_doorbell(ntb->epf);
 	return ret;
-- 
2.51.0