linux-kernel - [PATCH 5.15 213/779] PM: domains: Ensure genpd_debugfs

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Date:   Mon, 15 Aug 2022 19:57:37 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hsin-Yi Wang <hsinyi@...omium.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 213/779] PM: domains: Ensure genpd_debugfs_dir exists before remove

From: Hsin-Yi Wang <hsinyi@...omium.org>

[ Upstream commit 37101d3c719386040ded735a5ec06974f1d94d1f ]

Both genpd_debug_add() and genpd_debug_remove() may be called
indirectly by other drivers while genpd_debugfs_dir is not yet
set. For example, drivers can call pm_genpd_init() in probe or
pm_genpd_init() in probe fail/cleanup path:

pm_genpd_init()
 --> genpd_debug_add()

pm_genpd_remove()
 --> genpd_remove()
   --> genpd_debug_remove()

At this time, genpd_debug_init() may not yet be called.

genpd_debug_add() checks that if genpd_debugfs_dir is NULL, it
will return directly. Make sure this is also checked
in pm_genpd_remove(), otherwise components under debugfs root
which has the same name as other components under pm_genpd may
be accidentally removed, since NULL represents debugfs root.

Fixes: 718072ceb211 ("PM: domains: create debugfs nodes when adding power domains")
Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/base/power/domain.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 0f2e42f36851..7f3d21e6fdfb 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -219,6 +219,9 @@ static void genpd_debug_remove(struct generic_pm_domain *genpd)
 {
 	struct dentry *d;
 
+	if (!genpd_debugfs_dir)
+		return;
+
 	d = debugfs_lookup(genpd->name, genpd_debugfs_dir);
 	debugfs_remove(d);
 }
-- 
2.35.1