Commit 57f0060b authored by Ralf Baechle's avatar Ralf Baechle
Browse files

Document why calling smp_call_function will deadlock when called with 


interrupts disabled.

Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 26852d5c

arch/mips/kernel/smp.c

+13 −1
Original line number Diff line number Diff line
@@ -121,7 +121,19 @@ struct call_data_struct *call_data; 
 * or are or have executed.

 *

 * You must not call this function with disabled interrupts or from a

 * hardware interrupt handler or from a bottom half handler.

 * hardware interrupt handler or from a bottom half handler:

 *

 * CPU A                               CPU B

 * Disable interrupts

 *                                     smp_call_function()

 *                                     Take call_lock

 *                                     Send IPIs

 *                                     Wait for all cpus to acknowledge IPI

 *                                     CPU A has not responded, spin waiting

 *                                     for cpu A to respond, holding call_lock

 * smp_call_function()

 * Spin waiting for call_lock

 * Deadlock                            Deadlock

 */

int smp_call_function (void (*func) (void *info), void *info, int retry,

								int wait)