1 files changed, 17 insertions, 27 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index 4642a5c439eb..53d9a9ec88e6 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -39,6 +39,7 @@
 #include <linux/syslog.h>
 #include <linux/cpu.h>
 #include <linux/notifier.h>
+#include <linux/rculist.h>
 
 #include <asm/uaccess.h>
 
@@ -273,12 +274,12 @@ int do_syslog(int type, char __user *buf, int len, bool from_file)
 	 * at open time.
 	 */
 	if (type == SYSLOG_ACTION_OPEN || !from_file) {
-		if (dmesg_restrict && !capable(CAP_SYS_ADMIN))
-			return -EPERM;
+		if (dmesg_restrict && !capable(CAP_SYSLOG))
+			goto warn; /* switch to return -EPERM after 2.6.39 */
 		if ((type != SYSLOG_ACTION_READ_ALL &&
 		     type != SYSLOG_ACTION_SIZE_BUFFER) &&
-		    !capable(CAP_SYS_ADMIN))
-			return -EPERM;
+		    !capable(CAP_SYSLOG))
+			goto warn; /* switch to return -EPERM after 2.6.39 */
 	}
 
 	error = security_syslog(type);
@@ -422,6 +423,12 @@ int do_syslog(int type, char __user *buf, int len, bool from_file)
 	}
 out:
 	return error;
+warn:
+	/* remove after 2.6.39 */
+	if (capable(CAP_SYS_ADMIN))
+		WARN_ONCE(1, "Attempt to access syslog with CAP_SYS_ADMIN "
+		  "but no CAP_SYSLOG (deprecated and denied).\n");
+	return -EPERM;
 }
 
 SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len)
@@ -1496,7 +1503,7 @@ int kmsg_dump_register(struct kmsg_dumper *dumper)
 	/* Don't allow registering multiple times */
 	if (!dumper->registered) {
 		dumper->registered = 1;
-		list_add_tail(&dumper->list, &dump_list);
+		list_add_tail_rcu(&dumper->list, &dump_list);
 		err = 0;
 	}
 	spin_unlock_irqrestore(&dump_list_lock, flags);
@@ -1520,29 +1527,16 @@ int kmsg_dump_unregister(struct kmsg_dumper *dumper)
 	spin_lock_irqsave(&dump_list_lock, flags);
 	if (dumper->registered) {
 		dumper->registered = 0;
-		list_del(&dumper->list);
+		list_del_rcu(&dumper->list);
 		err = 0;
 	}
 	spin_unlock_irqrestore(&dump_list_lock, flags);
+	synchronize_rcu();
 
 	return err;
 }
 EXPORT_SYMBOL_GPL(kmsg_dump_unregister);
 
-static const char * const kmsg_reasons[] = {
-	[KMSG_DUMP_OOPS]	= "oops",
-	[KMSG_DUMP_PANIC]	= "panic",
-	[KMSG_DUMP_KEXEC]	= "kexec",
-};
-
-static const char *kmsg_to_str(enum kmsg_dump_reason reason)
-{
-	if (reason >= ARRAY_SIZE(kmsg_reasons) || reason < 0)
-		return "unknown";
-
-	return kmsg_reasons[reason];
-}
-
 /**
  * kmsg_dump - dump kernel log to kernel message dumpers.
  * @reason: the reason (oops, panic etc) for dumping
@@ -1581,13 +1575,9 @@ void kmsg_dump(enum kmsg_dump_reason reason)
 		l2 = chars;
 	}
 
-	if (!spin_trylock_irqsave(&dump_list_lock, flags)) {
-		printk(KERN_ERR "dump_kmsg: dump list lock is held during %s, skipping dump\n",
-				kmsg_to_str(reason));
-		return;
-	}
-	list_for_each_entry(dumper, &dump_list, list)
+	rcu_read_lock();
+	list_for_each_entry_rcu(dumper, &dump_list, list)
 		dumper->dump(dumper, reason, s1, l1, s2, l2);
-	spin_unlock_irqrestore(&dump_list_lock, flags);
+	rcu_read_unlock();
 }
 #endif