linux-kernel - [PATCH v2 02/23] interconnect: fix icc_provider

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Message-Id: <20230306075651.2449-3-johan+linaro@kernel.org>
Date:   Mon,  6 Mar 2023 08:56:30 +0100
From:   Johan Hovold <johan+linaro@...nel.org>
To:     Georgi Djakov <djakov@...nel.org>
Cc:     "Shawn Guo" <shawnguo@...nel.org>,
        "Sascha Hauer" <s.hauer@...gutronix.de>,
        "Pengutronix Kernel Team" <kernel@...gutronix.de>,
        "Fabio Estevam" <festevam@...il.com>,
        "NXP Linux Team" <linux-imx@....com>,
        "Andy Gross" <agross@...nel.org>,
        "Bjorn Andersson" <andersson@...nel.org>,
        "Konrad Dybcio" <konrad.dybcio@...aro.org>,
        "Sylwester Nawrocki" <s.nawrocki@...sung.com>,
        Artur Świgoń <a.swigon@...sung.com>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski@...aro.org>,
        "Alim Akhtar" <alim.akhtar@...sung.com>,
        "Thierry Reding" <thierry.reding@...il.com>,
        "Jonathan Hunter" <jonathanh@...dia.com>, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        Johan Hovold <johan+linaro@...nel.org>, stable@...r.kernel.org
Subject: [PATCH v2 02/23] interconnect: fix icc_provider_del() error handling

The interconnect framework currently expects that providers are only
removed when there are no users and after all nodes have been removed.

There is currently nothing that guarantees this to be the case and the
framework does not do any reference counting, but refusing to remove the
provider is never correct as that would leave a dangling pointer to a
resource that is about to be released in the global provider list (e.g.
accessible through debugfs).

Replace the current sanity checks with WARN_ON() so that the provider is
always removed.

Fixes: 11f1ceca7031 ("interconnect: Add generic on-chip interconnect API")
Cc: stable@...r.kernel.org      # 5.1: 680f8666baf6: interconnect: Make icc_provider_del() return void
Reviewed-by: Konrad Dybcio <konrad.dybcio@...aro.org>
Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
---
 drivers/interconnect/core.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index 5217f449eeec..cabb6f5df83e 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -1065,18 +1065,8 @@ EXPORT_SYMBOL_GPL(icc_provider_add);
 void icc_provider_del(struct icc_provider *provider)
 {
 	mutex_lock(&icc_lock);
-	if (provider->users) {
-		pr_warn("interconnect provider still has %d users\n",
-			provider->users);
-		mutex_unlock(&icc_lock);
-		return;
-	}
-
-	if (!list_empty(&provider->nodes)) {
-		pr_warn("interconnect provider still has nodes\n");
-		mutex_unlock(&icc_lock);
-		return;
-	}
+	WARN_ON(provider->users);
+	WARN_ON(!list_empty(&provider->nodes));
 
 	list_del(&provider->provider_list);
 	mutex_unlock(&icc_lock);
-- 
2.39.2