linux-kernel - [PATCH v4 2/6] phy: core: Fix that API devm_of_phy_provider_unregister() fails to unregister the phy provider

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Message-Id: <20241102-phy_core_fix-v4-2-4f06439f61b1@quicinc.com>
Date: Sat, 02 Nov 2024 11:53:44 +0800
From: Zijun Hu <zijun_hu@...oud.com>
To: Vinod Koul <vkoul@...nel.org>, 
 Kishon Vijay Abraham I <kishon@...nel.org>, Felipe Balbi <balbi@...com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Rob Herring <robh@...nel.org>, Arnd Bergmann <arnd@...db.de>, 
 Lee Jones <lee@...nel.org>
Cc: Lorenzo Pieralisi <lpieralisi@...nel.org>, 
 Krzysztof Wilczyński <kw@...ux.com>, 
 Bjorn Helgaas <bhelgaas@...gle.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Christophe JAILLET <christophe.jaillet@...adoo.fr>, 
 Johan Hovold <johan@...nel.org>, Zijun Hu <zijun_hu@...oud.com>, 
 stable@...r.kernel.org, linux-phy@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Zijun Hu <quic_zijuhu@...cinc.com>
Subject: [PATCH v4 2/6] phy: core: Fix that API
 devm_of_phy_provider_unregister() fails to unregister the phy provider

From: Zijun Hu <quic_zijuhu@...cinc.com>

For devm_of_phy_provider_unregister(), its comment says it needs to invoke
of_phy_provider_unregister() to unregister the phy provider, but it will
not actually invoke the function since devres_destroy() does not call
devm_phy_provider_release(), and the missing of_phy_provider_unregister()
call will case:

- The phy provider fails to be unregistered.
- Leak both memory and the OF node refcount.

Fortunately, the faulty API has not been used by current kernel tree.
Fixed by using devres_release() instead of devres_destroy() within the API.

Fixes: ff764963479a ("drivers: phy: add generic PHY framework")
Cc: stable@...r.kernel.org
Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.com>

---
Why to fix the API here instead of directly deleting it?

1) it is simpler, just one line change.
2) it may be used in future.
3) ensure this restored API right if need to restore it in future
   after deleting.

Anyone may remove such APIs separately later if he/she cares.
---
 drivers/phy/phy-core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
index f190d7126613..de07e1616b34 100644
--- a/drivers/phy/phy-core.c
+++ b/drivers/phy/phy-core.c
@@ -1259,12 +1259,12 @@ EXPORT_SYMBOL_GPL(of_phy_provider_unregister);
  * of_phy_provider_unregister to unregister the phy provider.
  */
 void devm_of_phy_provider_unregister(struct device *dev,
-	struct phy_provider *phy_provider)
+				     struct phy_provider *phy_provider)
 {
 	int r;

-	r = devres_destroy(dev, devm_phy_provider_release, devm_phy_match,
-		phy_provider);
+	r = devres_release(dev, devm_phy_provider_release, devm_phy_match,
+			   phy_provider);
 	dev_WARN_ONCE(dev, r, "couldn't find PHY provider device resource\n");
 }
 EXPORT_SYMBOL_GPL(devm_of_phy_provider_unregister);

-- 
2.34.1