The value of the "resource_alignment" can be specified using a kernel
command-line argument (using the "pci=resource_alignment=") or through
the corresponding sysfs object under the /sys/bus/pci path.
Currently, when the value is set via the kernel command-line argument,
and then subsequently accessed through sysfs object, the value read back
will not be correct, as per:
# grep -oE 'pci=resource_alignment.+' /proc/cmdline
pci=resource_alignment=20@00:1f.2
# cat /sys/bus/pci/resource_alignment
20@00:1f.
This is also true when the value is set through the sysfs object, but
the trailing newline has not been included, as per:
# echo -n 20@00:1f.2 > /sys/bus/pci/resource_alignment
# cat /sys/bus/pci/resource_alignment
20@00:1f.
When the value set through the sysfs object includes the trailing
newline, then reading it back will work as intended, as per:
# echo 20@00:1f.2 > /sys/bus/pci/resource_alignment
# cat /sys/bus/pci/resource_alignment
20@00:1f.2
To fix this inconsistency, append a trailing newline in the show()
function and strip the trailing line in the store() function if one is
present.
Also, allow for the value previously set using either a command-line
argument or through the sysfs object to be cleared at run-time.
Fixes: e499081da1a2 ("PCI: Force trailing new line to resource_alignment_param
in sysfs")
Signed-off-by: Krzysztof Wilczyński <k...@linux.com>
---
drivers/pci/pci.c | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 5ed316ea5831..7cde86bdcc8e 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -6439,34 +6439,37 @@ static ssize_t resource_alignment_show(struct bus_type
*bus, char *buf)
spin_lock(&resource_alignment_lock);
if (resource_alignment_param)
- count = sysfs_emit(buf, "%s", resource_alignment_param);
+ count = sysfs_emit(buf, "%s\n", resource_alignment_param);
spin_unlock(&resource_alignment_lock);
- /*
- * When set by the command line, resource_alignment_param will not
- * have a trailing line feed, which is ugly. So conditionally add
- * it here.
- */
- if (count >= 2 && buf[count - 2] != '\n' && count < PAGE_SIZE - 1) {
- buf[count - 1] = '\n';
- buf[count++] = 0;
- }
-
return count;
}
static ssize_t resource_alignment_store(struct bus_type *bus,
const char *buf, size_t count)
{
- char *param = kstrndup(buf, count, GFP_KERNEL);
+ char *param, *old, *end;
+ param = kstrndup(buf, count, GFP_KERNEL);
if (!param)
return -ENOMEM;
+ end = strchr(param, '\n');
+ if (end)
+ *end = '\0';
+
spin_lock(&resource_alignment_lock);
- kfree(resource_alignment_param);
- resource_alignment_param = param;
+ old = resource_alignment_param;
+ if (strlen(param)) {
+ resource_alignment_param = param;
+ } else {
+ kfree(resource_alignment_param);
+ resource_alignment_param = NULL;
+ }
spin_unlock(&resource_alignment_lock);
+
+ kfree(old);
+
return count;
}
--
2.31.1
