linux-kernel - [PATCH v2 3/3] PCI: Force trailing new line to resource_alignment

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Date:   Thu, 22 Aug 2019 10:10:13 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH v2 3/3] PCI: Force trailing new line to resource_alignment_param in sysfs

When 'pci=resource_alignment=' is specified on the command line, there
is no trailing new line.  Then, when it's read through the corresponding
sysfs attribute, there will be no newline and a cat command will not
show correctly in a shell. If the parameter is set through sysfs
a new line will be stored and it will 'cat' correctly.

To solve this, append a new line character in the show function if
one does not already exist.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
---
 drivers/pci/pci.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 5e00371149b1..4748362d6a49 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -6117,6 +6117,16 @@ static ssize_t resource_alignment_show(struct bus_type *bus, char *buf)
 		count = snprintf(buf, PAGE_SIZE, "%s", 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;
 }
 
-- 
2.20.1