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RDMA/rxe: Limit the number of calls to each tasklet

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[ Upstream commit eff6d998ca297cb0b2e53b032a56cf8e04dd8b17 ]

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.

Link: https://lore.kernel.org/r/20220630190425.2251-9-rpearsonhpe@gmail.com
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Bob Pearson
2022-06-30 14:04:25 -05:00
committed by Greg Kroah-Hartman
parent 9a6178c225
commit 18f62a453b
2 changed files with 18 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
drivers/infiniband/sw/rxe/rxe_param.h
View File

@@ -98,6 +98,12 @@ enum rxe_device_param {
RXE_INFLIGHT_SKBS_PER_QP_HIGH = 64, RXE_INFLIGHT_SKBS_PER_QP_HIGH = 64,
RXE_INFLIGHT_SKBS_PER_QP_LOW = 16, 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 */ /* Delay before calling arbiter timer */
RXE_NSEC_ARB_TIMER_DELAY = 200, RXE_NSEC_ARB_TIMER_DELAY = 200,

16
drivers/infiniband/sw/rxe/rxe_task.c
View File

@@ -8,7 +8,7 @@
#include <linux/interrupt.h> #include <linux/interrupt.h>
#include <linux/hardirq.h> #include <linux/hardirq.h>
#include "rxe_task.h" #include "rxe.h"
int __rxe_do_task(struct rxe_task *task) int __rxe_do_task(struct rxe_task *task)
@@ -34,6 +34,7 @@ void rxe_do_task(struct tasklet_struct *t)
int ret; int ret;
unsigned long flags; unsigned long flags;
struct rxe_task *task = from_tasklet(task, t, tasklet); struct rxe_task *task = from_tasklet(task, t, tasklet);
unsigned int iterations = RXE_MAX_ITERATIONS;
spin_lock_irqsave(&task->state_lock, flags); spin_lock_irqsave(&task->state_lock, flags);
switch (task->state) { switch (task->state) {
@@ -62,13 +63,20 @@ void rxe_do_task(struct tasklet_struct *t)
spin_lock_irqsave(&task->state_lock, flags); spin_lock_irqsave(&task->state_lock, flags);
switch (task->state) { switch (task->state) {
case TASK_STATE_BUSY: case TASK_STATE_BUSY:
if (ret) if (ret) {
task->state = TASK_STATE_START; task->state = TASK_STATE_START;
else } else if (iterations--) {
cont = 1; 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; 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 * func, so we will call one more time regardless of the
* return value * return value
*/ */