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authorAndres Salomon <dilinger@debian.org>2008-02-09 17:24:08 -0500
committerThomas Gleixner <tglx@linutronix.de>2008-02-09 17:24:08 -0500
commitf54ae69bafa16434ce46bc2f1fe556bce4d23650 (patch)
tree642ce77688984fc60c1f7d8dc2e7e8ad982c9cf9 /arch/x86/kernel
parentf087515c658a68454d43909d482ea4b59e7d6d5c (diff)
x86: GEODE: MFGPT: fix a potential race when disabling a timer
We *really* don't want to be reading MFGPTx_SETUP and writing back those values. What we want to be doing is clearing CMP1 and CMP2 unconditionally; otherwise, we have races where CMP1 and/or CMP2 fire after we've read MFGPTx_SETUP. They can also fire between when we've written ~CNTEN to the register, and when the new register values get copied to the timer's version of the register. By clearing both fields, we're okay. Signed-off-by: Andres Salomon <dilinger@debian.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/mfgpt_32.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/kernel/mfgpt_32.c b/arch/x86/kernel/mfgpt_32.c
index abdb7c71199a..81aa9db01f5f 100644
--- a/arch/x86/kernel/mfgpt_32.c
+++ b/arch/x86/kernel/mfgpt_32.c
@@ -249,8 +249,9 @@ __setup("mfgpt_irq=", mfgpt_setup);
249 249
250static void mfgpt_disable_timer(u16 clock) 250static void mfgpt_disable_timer(u16 clock)
251{ 251{
252 u16 val = geode_mfgpt_read(clock, MFGPT_REG_SETUP); 252 /* avoid races by clearing CMP1 and CMP2 unconditionally */
253 geode_mfgpt_write(clock, MFGPT_REG_SETUP, val & ~MFGPT_SETUP_CNTEN); 253 geode_mfgpt_write(clock, MFGPT_REG_SETUP, (u16) ~MFGPT_SETUP_CNTEN |
254 MFGPT_SETUP_CMP1 | MFGPT_SETUP_CMP2);
254} 255}
255 256
256static int mfgpt_next_event(unsigned long, struct clock_event_device *); 257static int mfgpt_next_event(unsigned long, struct clock_event_device *);