From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Date: Sat, 07 Nov 2009 18:58:13 -0000 > of_set_property_mutex is taken inside the devtree_lock write locked > region which triggers the might_sleep check. The mutex protects the > call to prom_setprop() which is not necessary as the code is the only > caller of prom_setprop() and already serialized by devtree_lock. The > mutex is nowhere else used despite being exported. So it can be > removed safely. > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Please see commit 2481d76615d5e15340ccfb0243fe8779766dfc6e to see why this mutex really is necessary, regardless of the locking done by the caller(s) of of_set_property(). And how it will thus need to be used in the future. The long and short of it is that the firmware uses I2C accesses to write the property values on some systems, and therefore the sparc64 I2C bus drivers will need this mutex to coordinate with callers of prom_set_property(). Those I2C drivers aren't merged yet, but I definitely plan to get them in soon :-) -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
