From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Andy Gross <agross@kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Ohad Ben-Cohen <ohad@wizery.com>
Cc: linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org,
linux-kernel@vger.kernel.org,
Mathieu Poirier <mathieu.poirier@linaro.org>
Subject: [PATCH v4 1/4] remoteproc: Traverse rproc_list under RCU read lock
Date: Mon, 9 Mar 2020 23:38:14 -0700 [thread overview]
Message-ID: <20200310063817.3344712-2-bjorn.andersson@linaro.org> (raw)
In-Reply-To: <20200310063817.3344712-1-bjorn.andersson@linaro.org>
In order to be able to traverse the mostly read-only rproc_list without
locking during panic migrate traversal to be done under rcu_read_lock().
Mutual exclusion for modifications of the list continues to be handled
by the rproc_list_mutex and a synchronization point is added before
releasing objects that are popped from the list.
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
Change v3:
- New patch
drivers/remoteproc/remoteproc_core.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 097f33e4f1f3..f0a77c30c6b1 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -1854,8 +1854,8 @@ struct rproc *rproc_get_by_phandle(phandle phandle)
if (!np)
return NULL;
- mutex_lock(&rproc_list_mutex);
- list_for_each_entry(r, &rproc_list, node) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(r, &rproc_list, node) {
if (r->dev.parent && r->dev.parent->of_node == np) {
/* prevent underlying implementation from being removed */
if (!try_module_get(r->dev.parent->driver->owner)) {
@@ -1868,7 +1868,7 @@ struct rproc *rproc_get_by_phandle(phandle phandle)
break;
}
}
- mutex_unlock(&rproc_list_mutex);
+ rcu_read_unlock();
of_node_put(np);
@@ -1925,7 +1925,7 @@ int rproc_add(struct rproc *rproc)
/* expose to rproc_get_by_phandle users */
mutex_lock(&rproc_list_mutex);
- list_add(&rproc->node, &rproc_list);
+ list_add_rcu(&rproc->node, &rproc_list);
mutex_unlock(&rproc_list_mutex);
return 0;
@@ -2140,9 +2140,12 @@ int rproc_del(struct rproc *rproc)
/* the rproc is downref'ed as soon as it's removed from the klist */
mutex_lock(&rproc_list_mutex);
- list_del(&rproc->node);
+ list_del_rcu(&rproc->node);
mutex_unlock(&rproc_list_mutex);
+ /* Ensure that no readers of rproc_list are still active */
+ synchronize_rcu();
+
device_del(&rproc->dev);
return 0;
--
2.24.0
next prev parent reply other threads:[~2020-03-10 6:39 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 6:38 [PATCH v4 0/4] remoteproc: Panic handling Bjorn Andersson
2020-03-10 6:38 ` Bjorn Andersson [this message]
2020-03-10 13:41 ` [PATCH v4 1/4] remoteproc: Traverse rproc_list under RCU read lock Arnaud POULIQUEN
2020-03-10 16:20 ` Bjorn Andersson
2020-03-23 21:52 ` Mathieu Poirier
2020-03-10 6:38 ` [PATCH v4 2/4] remoteproc: Introduce "panic" callback in ops Bjorn Andersson
2020-03-23 22:29 ` Mathieu Poirier
2020-03-23 22:33 ` Mathieu Poirier
2020-03-10 6:38 ` [PATCH v4 3/4] remoteproc: qcom: q6v5: Add common panic handler Bjorn Andersson
2020-03-23 22:36 ` Mathieu Poirier
2020-03-10 6:38 ` [PATCH v4 4/4] remoteproc: qcom: Introduce panic handler for PAS and ADSP Bjorn Andersson
2020-03-23 22:45 ` Mathieu Poirier
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