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author | Mike Tipton <quic_mdtipton@quicinc.com> | 2024-03-05 14:56:52 -0800 |
---|---|---|
committer | Georgi Djakov <djakov@kernel.org> | 2024-03-14 13:51:44 +0200 |
commit | de1bf25b6d771abdb52d43546cf57ad775fb68a1 (patch) | |
tree | 02220b64b65715f0fc429f1f5df8c658707418ab /drivers | |
parent | 59097a2a5ecadb0f025232c665fd11c8ae1e1f58 (diff) | |
download | linux-stable-de1bf25b6d771abdb52d43546cf57ad775fb68a1.tar.gz linux-stable-de1bf25b6d771abdb52d43546cf57ad775fb68a1.tar.bz2 linux-stable-de1bf25b6d771abdb52d43546cf57ad775fb68a1.zip |
interconnect: Don't access req_list while it's being manipulated
The icc_lock mutex was split into separate icc_lock and icc_bw_lock
mutexes in [1] to avoid lockdep splats. However, this didn't adequately
protect access to icc_node::req_list.
The icc_set_bw() function will eventually iterate over req_list while
only holding icc_bw_lock, but req_list can be modified while only
holding icc_lock. This causes races between icc_set_bw(), of_icc_get(),
and icc_put().
Example A:
CPU0 CPU1
---- ----
icc_set_bw(path_a)
mutex_lock(&icc_bw_lock);
icc_put(path_b)
mutex_lock(&icc_lock);
aggregate_requests()
hlist_for_each_entry(r, ...
hlist_del(...
<r = invalid pointer>
Example B:
CPU0 CPU1
---- ----
icc_set_bw(path_a)
mutex_lock(&icc_bw_lock);
path_b = of_icc_get()
of_icc_get_by_index()
mutex_lock(&icc_lock);
path_find()
path_init()
aggregate_requests()
hlist_for_each_entry(r, ...
hlist_add_head(...
<r = invalid pointer>
Fix this by ensuring icc_bw_lock is always held before manipulating
icc_node::req_list. The additional places icc_bw_lock is held don't
perform any memory allocations, so we should still be safe from the
original lockdep splats that motivated the separate locks.
[1] commit af42269c3523 ("interconnect: Fix locking for runpm vs reclaim")
Signed-off-by: Mike Tipton <quic_mdtipton@quicinc.com>
Fixes: af42269c3523 ("interconnect: Fix locking for runpm vs reclaim")
Reviewed-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20240305225652.22872-1-quic_mdtipton@quicinc.com
Signed-off-by: Georgi Djakov <djakov@kernel.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/interconnect/core.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c index 50bac2d79d9b..68edb07d4443 100644 --- a/drivers/interconnect/core.c +++ b/drivers/interconnect/core.c @@ -176,6 +176,8 @@ static struct icc_path *path_init(struct device *dev, struct icc_node *dst, path->num_nodes = num_nodes; + mutex_lock(&icc_bw_lock); + for (i = num_nodes - 1; i >= 0; i--) { node->provider->users++; hlist_add_head(&path->reqs[i].req_node, &node->req_list); @@ -186,6 +188,8 @@ static struct icc_path *path_init(struct device *dev, struct icc_node *dst, node = node->reverse; } + mutex_unlock(&icc_bw_lock); + return path; } @@ -792,12 +796,16 @@ void icc_put(struct icc_path *path) pr_err("%s: error (%d)\n", __func__, ret); mutex_lock(&icc_lock); + mutex_lock(&icc_bw_lock); + for (i = 0; i < path->num_nodes; i++) { node = path->reqs[i].node; hlist_del(&path->reqs[i].req_node); if (!WARN_ON(!node->provider->users)) node->provider->users--; } + + mutex_unlock(&icc_bw_lock); mutex_unlock(&icc_lock); kfree_const(path->name); |