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nvme/multipath: Fix RCU list traversal to use SRCU primitive

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The code currently uses list_for_each_entry_rcu() while holding an SRCU
lock, triggering false positive warnings with CONFIG_PROVE_RCU=y
enabled:

	drivers/nvme/host/multipath.c:168 RCU-list traversed in non-reader section!!
	drivers/nvme/host/multipath.c:227 RCU-list traversed in non-reader section!!
	drivers/nvme/host/multipath.c:260 RCU-list traversed in non-reader section!!

While the list is properly protected by SRCU lock, the code uses the
wrong list traversal primitive. Replace list_for_each_entry_rcu() with
list_for_each_entry_srcu() to correctly indicate SRCU-based protection
and eliminate the false warning.

Signed-off-by: Breno Leitao <leitao@debian.org>
Fixes: be647e2c76 ("nvme: use srcu for iterating namespace list")
Signed-off-by: Keith Busch <kbusch@kernel.org>
This commit is contained in:
Breno Leitao
2024-11-05 06:42:46 -08:00
committed by Keith Busch
parent a3f143c461
commit 5dd18f09ce
1 changed files with 14 additions and 7 deletions
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21
drivers/nvme/host/multipath.c
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@@ -165,7 +165,8 @@ void nvme_kick_requeue_lists(struct nvme_ctrl *ctrl)
int srcu_idx;
srcu_idx = srcu_read_lock(&ctrl->srcu);
list_for_each_entry_rcu(ns, &ctrl->namespaces, list) {
list_for_each_entry_srcu(ns, &ctrl->namespaces, list,
srcu_read_lock_held(&ctrl->srcu)) {
if (!ns->head->disk)
continue;
kblockd_schedule_work(&ns->head->requeue_work);
@@ -209,7 +210,8 @@ void nvme_mpath_clear_ctrl_paths(struct nvme_ctrl *ctrl)
int srcu_idx;
srcu_idx = srcu_read_lock(&ctrl->srcu);
list_for_each_entry_rcu(ns, &ctrl->namespaces, list) {
list_for_each_entry_srcu(ns, &ctrl->namespaces, list,
srcu_read_lock_held(&ctrl->srcu)) {
nvme_mpath_clear_current_path(ns);
kblockd_schedule_work(&ns->head->requeue_work);
}
@@ -224,7 +226,8 @@ void nvme_mpath_revalidate_paths(struct nvme_ns *ns)
int srcu_idx;
srcu_idx = srcu_read_lock(&head->srcu);
list_for_each_entry_rcu(ns, &head->list, siblings) {
list_for_each_entry_srcu(ns, &head->list, siblings,
srcu_read_lock_held(&head->srcu)) {
if (capacity != get_capacity(ns->disk))
clear_bit(NVME_NS_READY, &ns->flags);
}
@@ -257,7 +260,8 @@ static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head, int node)
int found_distance = INT_MAX, fallback_distance = INT_MAX, distance;
struct nvme_ns *found = NULL, *fallback = NULL, *ns;
list_for_each_entry_rcu(ns, &head->list, siblings) {
list_for_each_entry_srcu(ns, &head->list, siblings,
srcu_read_lock_held(&head->srcu)) {
if (nvme_path_is_disabled(ns))
continue;
@@ -356,7 +360,8 @@ static struct nvme_ns *nvme_queue_depth_path(struct nvme_ns_head *head)
unsigned int min_depth_opt = UINT_MAX, min_depth_nonopt = UINT_MAX;
unsigned int depth;
list_for_each_entry_rcu(ns, &head->list, siblings) {
list_for_each_entry_srcu(ns, &head->list, siblings,
srcu_read_lock_held(&head->srcu)) {
if (nvme_path_is_disabled(ns))
continue;
@@ -424,7 +429,8 @@ static bool nvme_available_path(struct nvme_ns_head *head)
if (!test_bit(NVME_NSHEAD_DISK_LIVE, &head->flags))
return NULL;
list_for_each_entry_rcu(ns, &head->list, siblings) {
list_for_each_entry_srcu(ns, &head->list, siblings,
srcu_read_lock_held(&head->srcu)) {
if (test_bit(NVME_CTRL_FAILFAST_EXPIRED, &ns->ctrl->flags))
continue;
switch (nvme_ctrl_state(ns->ctrl)) {
@@ -783,7 +789,8 @@ static int nvme_update_ana_state(struct nvme_ctrl *ctrl,
return 0;
srcu_idx = srcu_read_lock(&ctrl->srcu);
list_for_each_entry_rcu(ns, &ctrl->namespaces, list) {
list_for_each_entry_srcu(ns, &ctrl->namespaces, list,
srcu_read_lock_held(&ctrl->srcu)) {
unsigned nsid;
again:
nsid = le32_to_cpu(desc->nsids[n]);