On Wed, Sep 12, 2012 at 02:50:10PM +0300, Roger Quadros wrote: > gets rid of below messages with CONFIG_DEBUG_PREEMPT enabled > > [ 28.832916] debug_smp_processor_id: 18 callbacks suppressed > [ 28.832946] BUG: using smp_processor_id() in preemptible [00000000] code: modprobe/1763 > [ 28.841491] caller is pwrdm_set_next_pwrst+0x54/0x120 > > Tested with perf on OMAP4 Panda. NAK. Using a different function which doesn't have the warning isn't a subsitute for fixing the problem properly. What you're doing is papering over the bug, making the warning go away without properly understanding the problem. The warning is there because something is being done wrong. What that is is exactly what is being said in the warning message. You're getting a CPU number in a context where preemptions can occur - and therefore the CPU that you're running on can change. Think about this sequence: - cpu = smp_processor_id(); /* returns 0 */ - you are preempted - you resume on CPU 1 - trace_clock_disable(clk->name, 0, 0); If trace_clock_disable() uses the CPU number to access per-CPU data without locking, that's going to cause corruption. Please, if you're going to fix a warning, analyse it properly first and don't just search for a function which appears to give you the same functionality but without the warning message. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
