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| author |   Trent Piepho <xyzzy@speakeasy.org> | 2006-05-15 09:44:06 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@g5.osdl.org> | 2006-05-15 11:20:55 -0700 |
| commit | 5e376613899076396d0c97de67ad072587267370 (patch) | |
| tree | ecc15c25ee4da7754aa7d137dccebab68820399e /kernel | |
| parent | [PATCH] s390: add vmsplice system call (diff) | |
| download | linux-dev-5e376613899076396d0c97de67ad072587267370.tar.xz linux-dev-5e376613899076396d0c97de67ad072587267370.zip | |
[PATCH] symbol_put_addr() locks kernel
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>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/extable.c | 2 | ||||
| -rw-r--r-- | kernel/module.c | 12 |
2 files changed, 7 insertions, 7 deletions
diff --git a/kernel/extable.c b/kernel/extable.c index 7501b531ceed..7fe262855317 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -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) diff --git a/kernel/module.c b/kernel/module.c index d24deb0dbbc9..bbe04862e1b0 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -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); |