[PATCH 3/3] PCI: Force trailing new line to resource_alignment_param in sysfs

From: Logan Gunthorpe <logang@deltatee.com>
To: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	Logan Gunthorpe <logang@deltatee.com>
Subject: [PATCH 3/3] PCI: Force trailing new line to resource_alignment_param in sysfs
Date: Fri, 24 May 2019 14:16:10 -0600	[thread overview]
Message-ID: <20190524201610.8039-4-logang@deltatee.com> (raw)
In-Reply-To: <20190524201610.8039-1-logang@deltatee.com>

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@deltatee.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/pci.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 3e71e161f18b..99d130ac6b96 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -6090,6 +6090,16 @@ 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

