linux-kernel - [PATCH][trivial] mISDN: l1oip - reduce stack memory footprint

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Date:	Wed, 25 Feb 2009 16:54:56 +0100
From:	Frank Seidel <fseidel@...e.de>
To:	linux kernel <linux-kernel@...r.kernel.org>
Cc:	akpm@...ux-foundation.org, linux-isdn@...r.kernel.org,
	Frank Seidel <fseidel@...e.de>,
	Frank Seidel <frank@...eidel.de>, jolly@...rsberg.eu,
	kkeil@...e.de, smurf@...rf.noris.de, andreas@...rsberg.eu,
	hannes@...neseder.net
Subject: [PATCH][trivial] mISDN: l1oip - reduce stack memory footprint

From: Frank Seidel <frank@...eidel.de>

Applying kernel janitors todos (reduce stack
footprint where possible) to l1oip mISDN driver.
(Before 1656 bytes on i386, now 164)

Signed-off-by: Frank Seidel <frank@...eidel.de>
---
 drivers/isdn/mISDN/l1oip_core.c |   21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

--- a/drivers/isdn/mISDN/l1oip_core.c
+++ b/drivers/isdn/mISDN/l1oip_core.c
@@ -663,18 +663,28 @@ l1oip_socket_thread(void *data)
 	struct iovec iov;
 	mm_segment_t oldfs;
 	struct sockaddr_in sin_rx;
-	unsigned char recvbuf[1500];
+	unsigned char *recvbuf;
+	size_t recvbuf_size = 1500;
 	int recvlen;
 	struct socket *socket = NULL;
 	DECLARE_COMPLETION(wait);
 
+	/* allocate buffer memory */
+	recvbuf = kmalloc(recvbuf_size * sizeof(*recvbuf), GFP_KERNEL);
+	if (!recvbuf) {
+		printk(KERN_ERR "%s: Failed to allocate memory.\n", __func__);
+		ret = -ENOMEM;
+		goto out;
+	}
+
 	/* make daemon */
 	allow_signal(SIGTERM);
 
 	/* create socket */
 	if (sock_create(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &socket)) {
 		printk(KERN_ERR "%s: Failed to create socket.\n", __func__);
-		return -EIO;
+		ret = -EIO;
+		goto out;
 	}
 
 	/* set incoming address */
@@ -730,10 +740,10 @@ l1oip_socket_thread(void *data)
 			__func__);
 	while (!signal_pending(current)) {
 		iov.iov_base = recvbuf;
-		iov.iov_len = sizeof(recvbuf);
+		iov.iov_len = recvbuf_size;
 		oldfs = get_fs();
 		set_fs(KERNEL_DS);
-		recvlen = sock_recvmsg(socket, &msg, sizeof(recvbuf), 0);
+		recvlen = sock_recvmsg(socket, &msg, recvbuf_size, 0);
 		set_fs(oldfs);
 		if (recvlen > 0) {
 			l1oip_socket_parse(hc, &sin_rx, recvbuf, recvlen);
@@ -771,6 +781,9 @@ fail:
 	if (debug & DEBUG_L1OIP_SOCKET)
 		printk(KERN_DEBUG "%s: socket thread terminated\n",
 			__func__);
+
+out:
+	kfree(recvbuf);
 	return ret;
 }
 
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