From mboxrd@z Thu Jan  1 00:00:00 1970
From: George Beshers <gbeshers@sgi.com>
Date: Mon, 05 Mar 2007 20:34:44 +0000
Subject: PATCH udev-106 /proc/stat buffer to small
Message-Id: <45EC7EE4.5000903@sgi.com>
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List-Id: <linux-hotplug.vger.kernel.org>
To: linux-hotplug@vger.kernel.org

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I am assuming that this is the correct place to post udev patches for
consideration, feel free to inform me otherwise :-).

George


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This came up on a system with 1024cores (well 768cpus and 256
hyper-threads) where the buffer size for reading /proc/stat was
not large enough causing udev to fail during the boot process.
The read_proc_stat(void) eliminates this problem.

routine makes sure that the 

--- udev-105/udevd.c	2007-02-02 19:24:48.000000000 -0500
+++ udev-105.new/udevd.c	2007-02-19 13:47:54.000000000 -0500
@@ -357,25 +357,58 @@
 	return memsize / 1024;
 }
 
-static int cpu_count(void)
+/*
+ * Use the same buffer for cpu_count() and running_processes()
+ */
+
+static char* stat_buf = NULL;
+static int   stat_buf_size = 4096;
+
+static int read_proc_stat(void)
 {
 	int f;
-	char buf[32768];
 	int len;
-	const char *pos;
-	int count = 0;
 
-	f = open("/proc/stat", O_RDONLY);
-	if (f == -1)
-		return -1;
+	if (stat_buf == NULL) {
+		stat_buf = malloc(stat_buf_size);
+		if (stat_buf == NULL)
+			return -1;
+	}
 
-	len = read(f, buf, sizeof(buf)-1);
+	do {
+		f = open("/proc/stat", O_RDONLY);
+		if (f == -1)
+			return -1;
+
+		len = read(f, stat_buf, stat_buf_size-1);
+		if (len < stat_buf_size-1)
+			break;
+
+		stat_buf_size *= 2;
+		stat_buf = realloc(stat_buf, stat_buf_size);
+		if (stat_buf == NULL)
+			return -1;
+	} while (1);
 	close(f);
+
 	if (len <= 0)
 		return -1;
-	buf[len] = '\0';
+	stat_buf[len] = '\0';
+	return len;
+}
+
 
-	pos = strstr(buf, "cpu");
+static int cpu_count(void)
+{
+	int len;
+	const char *pos;
+	int count = 0;
+
+	len = read_proc_stat();
+	if (len <= 0)
+		return -1;
+
+	pos = strstr(stat_buf, "cpu");
 	if (pos == NULL)
 		return -1;
 
@@ -392,23 +425,15 @@
 
 static int running_processes(void)
 {
-	int f;
-	char buf[32768];
 	int len;
 	int running;
 	const char *pos;
 
-	f = open("/proc/stat", O_RDONLY);
-	if (f == -1)
-		return -1;
-
-	len = read(f, buf, sizeof(buf)-1);
-	close(f);
+	len = read_proc_stat();
 	if (len <= 0)
 		return -1;
-	buf[len] = '\0';
 
-	pos = strstr(buf, "procs_running ");
+	pos = strstr(stat_buf, "procs_running ");
 	if (pos == NULL)
 		return -1;
 

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