From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Date: Wed, 3 Nov 2021 21:16:53 +0000 (+0100)
Subject: PCI/P2PDMA: Use percpu_ref_tryget_live_rcu() inside RCU critical section
X-Git-Tag: v5.17-rc1~73^2~23^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=69f457b18fa2b9a793ce61e8d1cf295983aca3a9;p=thirdparty%2Fkernel%2Flinux.git

PCI/P2PDMA: Use percpu_ref_tryget_live_rcu() inside RCU critical section

Since pci_alloc_p2pmem() has already called rcu_read_lock(), we're in an
RCU read-side critical section and don't need to take the lock again.  Use
percpu_ref_tryget_live_rcu() instead of percpu_ref_tryget_live() to save a
few cycles.

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/ab80164f4d5b32f9e6240aa4863c3a147ff9c89f.1635974126.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Krzysztof Wilczyński <kw@linux.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
---

diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 8d47cb7218d15..081c391690d45 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -710,7 +710,7 @@ void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size)
 	if (!ret)
 		goto out;
 
-	if (unlikely(!percpu_ref_tryget_live(ref))) {
+	if (unlikely(!percpu_ref_tryget_live_rcu(ref))) {
 		gen_pool_free(p2pdma->pool, (unsigned long) ret, size);
 		ret = NULL;
 		goto out;