[PATCH] symbol_put_addr() locks kernel (5e376613) · Commits · 戴 / test

Even since a previous patch: Fix race between CONFIG_DEBUG_SLABALLOC and modules Sun, 27 Jun 2004 17:55:19 +0000 (17:55 +0000) http://www.kernel.org/git/?p=linux/kernel/git/torvalds/old-2.6-bkcvs.git;a=commit;h=92b3db26d31cf21b70e3c1eadc56c179506d8fbe The function symbol_put_addr() will deadlock the kernel. 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> Cc: Zwane Mwaikambo <zwane@fsmlabs.com> Acked-by:

Rusty Russell <rusty@rustcorp.com.au> Cc: Johannes Stezenbach <js@linuxtv.org> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

include/linux/kernel.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -124,6 +124,7 @@ extern int get_option(char *str, int pint);
		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);

kernel/extable.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -40,7 +40,7 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
		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)

kernel/module.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -705,14 +705,14 @@ EXPORT_SYMBOL(__symbol_put);

		void symbol_put_addr(void *addr)
		{
		unsigned long flags;
		struct module *modaddr;

		spin_lock_irqsave(&modlist_lock, flags);
		if (!kernel_text_address((unsigned long)addr))
		BUG();
		if (core_kernel_text((unsigned long)addr))
		return;

		module_put(module_text_address((unsigned long)addr));
		spin_unlock_irqrestore(&modlist_lock, flags);
		if (!(modaddr = module_text_address((unsigned long)addr)))
		BUG();
		module_put(modaddr);
		}
		EXPORT_SYMBOL_GPL(symbol_put_addr);

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