[PATCH] remove the syslog interface when printk is disabled

Attempts to read() from the non-existent dmesg buffer will return zero and
userspace tends to get stuck in a busyloop.

So just remove /dev/kmsg altogether if CONFIG_PRINTK=n.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 5 insertions, 7 deletions

diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index 7431d7ba2d09..f6c776272572 100644
--- a/fs/proc/Makefile
+++ b/fs/proc/Makefile
@@ -8,8 +8,9 @@ proc-y			:= nommu.o task_nommu.o
 proc-$(CONFIG_MMU)      := mmu.o task_mmu.o
 
 proc-y       += inode.o root.o base.o generic.o array.o \
-                kmsg.o proc_tty.o proc_misc.o
+                proc_tty.o proc_misc.o
 
 proc-$(CONFIG_PROC_KCORE)       += kcore.o
 proc-$(CONFIG_PROC_VMCORE)      += vmcore.o
 proc-$(CONFIG_PROC_DEVICETREE)  += proc_devtree.o
+proc-$(CONFIG_PRINTK)   += kmsg.o
diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index 93c43b676e59..51815cece6f3 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -696,9 +696,11 @@ void __init proc_misc_init(void)
         proc_symlink("mounts", NULL, "self/mounts");
 
         /* And now for trickier ones */
+#ifdef CONFIG_PRINTK
         entry = create_proc_entry("kmsg", S_IRUSR, &proc_root);
         if (entry)
                 entry->proc_fops = &proc_kmsg_operations;
+#endif
         create_seq_entry("devices", 0, &proc_devinfo_operations);
         create_seq_entry("cpuinfo", 0, &proc_cpuinfo_operations);
 #ifdef CONFIG_BLOCK
diff --git a/kernel/printk.c b/kernel/printk.c
index 66426552fbfe..ba59c2a30ed0 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -631,12 +631,7 @@ EXPORT_SYMBOL(vprintk);
 
 asmlinkage long sys_syslog(int type, char __user *buf, int len)
 {
-        return 0;
-}
-
-int do_syslog(int type, char __user *buf, int len)
-{
-        return 0;
+        return -ENOSYS;
 }
 
 static void call_console_drivers(unsigned long start, unsigned long end)