@@ -105,6 +105,12 @@ enum rxe_device_param {
RXE_INFLIGHT_SKBS_PER_QP_HIGH = 64,
RXE_INFLIGHT_SKBS_PER_QP_LOW = 16,
+ /* Max number of interations of each tasklet
+ * before yielding the cpu to let other
+ * work make progress
+ */
+ RXE_MAX_ITERATIONS = 1024,
+
/* Delay before calling arbiter timer */
RXE_NSEC_ARB_TIMER_DELAY = 200,
@@ -8,7 +8,7 @@
#include <linux/interrupt.h>
#include <linux/hardirq.h>
-#include "rxe_task.h"
+#include "rxe.h"
int __rxe_do_task(struct rxe_task *task)
@@ -33,6 +33,7 @@ void rxe_do_task(struct tasklet_struct *t)
int cont;
int ret;
struct rxe_task *task = from_tasklet(task, t, tasklet);
+ unsigned int iterations = RXE_MAX_ITERATIONS;
spin_lock_bh(&task->state_lock);
switch (task->state) {
@@ -61,13 +62,20 @@ void rxe_do_task(struct tasklet_struct *t)
spin_lock_bh(&task->state_lock);
switch (task->state) {
case TASK_STATE_BUSY:
- if (ret)
+ if (ret) {
task->state = TASK_STATE_START;
- else
+ } else if (iterations--) {
cont = 1;
+ } else {
+ /* reschedule the tasklet and exit
+ * the loop to give up the cpu
+ */
+ tasklet_schedule(&task->tasklet);
+ task->state = TASK_STATE_START;
+ }
break;
- /* soneone tried to run the task since the last time we called
+ /* someone tried to run the task since the last time we called
* func, so we will call one more time regardless of the
* return value
*/
Limit the maximum number of calls to each tasklet from rxe_do_task() before yielding the cpu. When the limit is reached reschedule the tasklet and exit the calling loop. This patch prevents one tasklet from consuming 100% of a cpu core and causing a deadlock or soft lockup. Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com> --- drivers/infiniband/sw/rxe/rxe_param.h | 6 ++++++ drivers/infiniband/sw/rxe/rxe_task.c | 16 ++++++++++++---- 2 files changed, 18 insertions(+), 4 deletions(-)