[PATCH v2 -next] PCI: Don't use GFP_KERNEL for kstrbdup in resource_alignment_store

From: YueHaibing <yuehaibing@huawei.com>
To: <bhelgaas@google.com>, <hch@infradead.org>
Cc: <linux-pci@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	YueHaibing <yuehaibing@huawei.com>
Subject: [PATCH v2 -next] PCI: Don't use GFP_KERNEL for kstrbdup in resource_alignment_store
Date: Tue, 3 Sep 2019 16:22:29 +0800	[thread overview]
Message-ID: <20190903082229.21488-1-yuehaibing@huawei.com> (raw)
In-Reply-To: <20190831124932.18759-1-yuehaibing@huawei.com>

When allocating memory, the GFP_KERNEL cannot be used during the
spin_lock period. It may cause scheduling when holding spin_lock.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Fixes: f13755318675 ("PCI: Move pci_[get|set]_resource_alignment_param() into their callers")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
---
v2: move alloc out of spinlock
---
 drivers/pci/pci.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 484e353..a3d5920 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -6145,14 +6145,17 @@ static ssize_t resource_alignment_show(struct bus_type *bus, char *buf)
 static ssize_t resource_alignment_store(struct bus_type *bus,
 					const char *buf, size_t count)
 {
-	spin_lock(&resource_alignment_lock);
+	char *param = kstrndup(buf, count, GFP_KERNEL);
 
-	kfree(resource_alignment_param);
-	resource_alignment_param = kstrndup(buf, count, GFP_KERNEL);
+	if (!param)
+		return -ENOMEM;
 
+	spin_lock(&resource_alignment_lock);
+	kfree(resource_alignment_param);
+	resource_alignment_param = param;
 	spin_unlock(&resource_alignment_lock);
 
-	return resource_alignment_param ? count : -ENOMEM;
+	return count;
 }
 
 static BUS_ATTR_RW(resource_alignment);
-- 
2.7.4


