linux-kernel - [PATCH] of: restricted dma: Fix condition for rmem init

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Message-Id: <20210917131423.2760155-1-dbrazdil@google.com>
Date:   Fri, 17 Sep 2021 14:14:23 +0100
From:   David Brazdil <dbrazdil@...gle.com>
To:     devicetree@...r.kernel.org
Cc:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Will Deacon <will@...nel.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        linux-kernel@...r.kernel.org, David Brazdil <dbrazdil@...gle.com>
Subject: [PATCH] of: restricted dma: Fix condition for rmem init

of_dma_set_restricted_buffer fails to handle negative return values from
of_property_count_elems_of_size, e.g. when the property does not exist.
This results in an attempt to assign a non-existent reserved memory
region to the device and a warning being printed. Fix the condition to
take negative values into account.

Fixes: f3cfd136aef0 ("of: restricted dma: Don't fail device probe on
rmem init failure")
Cc: Will Deacon <will@...nel.org>
Signed-off-by: David Brazdil <dbrazdil@...gle.com>
---
 drivers/of/device.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 5b043ee30824..b0800c260f64 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -85,7 +85,11 @@ of_dma_set_restricted_buffer(struct device *dev, struct device_node *np)
 			break;
 	}
 
-	if (i != count && of_reserved_mem_device_init_by_idx(dev, of_node, i))
+	/*
+	 * Attempt to initialize a restricted-dma-pool region if one was found.
+	 * Note that count can hold a negative error code.
+	 */
+	if (i < count && of_reserved_mem_device_init_by_idx(dev, of_node, i))
 		dev_warn(dev, "failed to initialise \"restricted-dma-pool\" memory node\n");
 }
 
-- 
2.33.0.464.g1972c5931b-goog