# HG changeset patch
# User Trent Piepho <xyzzy@speakeasy.org>
# Node ID b66f3aa4bfe88f9ea2edb9c87419413ecc6caa8c
# Parent  4c3f241d7bc53fc25ddab54140f96cacd71ae1e1
From: Trent Piepho <xyzzy@speakeasy.org>

symbol_put_addr() would acquire modlist_lock, then while holding the lock call
two functions kernel_text_address() and module_text_address() which also try
to acquire the same lock.  This deadlocks the kernel of course.

This patch changes symbol_put_addr() to not acquire the modlist_lock, it
doesn't need it since it never looks at the module list directly.  Also, it
now uses core_kernel_text() instead of kernel_text_address().  The latter
has an additional check for addr inside a module, but we don't need to do that
since we call module_text_address() (the same function kernel_text_address
uses) ourselves.


Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>

 
 include/linux/kernel.h |    1 +
 kernel/extable.c       |    2 +-
 kernel/module.c        |   14 +++++++-------
 3 files changed, 9 insertions(+), 8 deletions(-)

diff -r 4c3f241d7bc5 -r b66f3aa4bfe8 include/linux/kernel.h
--- a/include/linux/kernel.h	Fri Apr 28 23:00:35 2006 +0700
+++ b/include/linux/kernel.h	Fri Apr 28 14:49:34 2006 -0700
@@ -124,6 +124,7 @@ extern char *get_options(const char *str
 extern char *get_options(const char *str, int nints, int *ints);
 extern unsigned long long memparse(char *ptr, char **retptr);
 
+extern int core_kernel_text(unsigned long addr);
 extern int __kernel_text_address(unsigned long addr);
 extern int kernel_text_address(unsigned long addr);
 extern int session_of_pgrp(int pgrp);
diff -r 4c3f241d7bc5 -r b66f3aa4bfe8 kernel/extable.c
--- a/kernel/extable.c	Fri Apr 28 23:00:35 2006 +0700
+++ b/kernel/extable.c	Fri Apr 28 14:49:34 2006 -0700
@@ -40,7 +40,7 @@ const struct exception_table_entry *sear
 	return e;
 }
 
-static int core_kernel_text(unsigned long addr)
+int core_kernel_text(unsigned long addr)
 {
 	if (addr >= (unsigned long)_stext &&
 	    addr <= (unsigned long)_etext)
diff -r 4c3f241d7bc5 -r b66f3aa4bfe8 kernel/module.c
--- a/kernel/module.c	Fri Apr 28 23:00:35 2006 +0700
+++ b/kernel/module.c	Fri Apr 28 14:49:34 2006 -0700
@@ -705,14 +705,14 @@ EXPORT_SYMBOL(__symbol_put);
 
 void symbol_put_addr(void *addr)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&modlist_lock, flags);
-	if (!kernel_text_address((unsigned long)addr))
+	struct module *modaddr;
+
+	if (core_kernel_text((unsigned long)addr))
+		return;
+
+	if (!(modaddr = module_text_address((unsigned long)addr)))
 		BUG();
-
-	module_put(module_text_address((unsigned long)addr));
-	spin_unlock_irqrestore(&modlist_lock, flags);
+	module_put(modaddr);
 }
 EXPORT_SYMBOL_GPL(symbol_put_addr);