Messages in this thread | | | Subject | Re: [PATCH] Fix CPU spinlock lockups on secondary CPU bringup | From | Eric Dumazet <> | Date | Wed, 22 Jun 2011 20:46:48 +0200 |
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Le mercredi 22 juin 2011 à 11:55 +0100, Russell King - ARM Linux a écrit : > From: Russell King <rmk+kernel@arm.linux.org.uk> > > Secondary CPU bringup typically calls calibrate_delay() during its > initialization. However, calibrate_delay() modifies a global variable > (loops_per_jiffy) used for udelay() and __delay(). > > A side effect of 71c696b1 (calibrate: extract fall-back calculation > into own helper) introduced in the 2.6.39 merge window means that we > end up with a substantial period where loops_per_jiffy is zero. This > causes the spinlock debugging code to malfunction: ...
> > + loops_per_jiffy = lpj; > printed = true; > }
To be 100% safe, I would use
ACCESS_ONCE(loops_per_jiffy) = lpj;
But I assume no current gcc would be that stupid ;)
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