linux-kernel - [PATCH v1 1/5] devres: Fix devm

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Message-ID: <1719931914-19035-2-git-send-email-quic_zijuhu@quicinc.com>
Date: Tue, 2 Jul 2024 22:51:50 +0800
From: Zijun Hu <quic_zijuhu@...cinc.com>
To: <linux-kernel@...r.kernel.org>
CC: <gregkh@...uxfoundation.org>, <rafael@...nel.org>, <brgl@...ev.pl>,
        <madalin.bucur@....com>, <davem@...emloft.net>,
        <andriy.shevchenko@...ux.intel.com>, <stable@...r.kernel.org>,
        Zijun Hu
	<quic_zijuhu@...cinc.com>
Subject: [PATCH v1 1/5] devres: Fix devm_krealloc() wasting memory

Driver API devm_krealloc() calls alloc_dr() with wrong argument
@total_new_size, so causes more memory to be allocated than required
fix this memory waste by using @new_size as the argument for alloc_dr().

Fixes: f82485722e5d ("devres: provide devm_krealloc()")
Cc: stable@...r.kernel.org
Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.com>
---
Previous discussion link:
https://lore.kernel.org/all/1718531655-29761-1-git-send-email-quic_zijuhu@quicinc.com/

Changes since the original one:
 - Correct tile and commit message
 - Add inline comments and stable tag

 drivers/base/devres.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index 3df0025d12aa..ff2247eec43c 100644
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -896,9 +896,12 @@ void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
 	/*
 	 * Otherwise: allocate new, larger chunk. We need to allocate before
 	 * taking the lock as most probably the caller uses GFP_KERNEL.
+	 * alloc_dr() will call check_dr_size() to reserve extra memory
+	 * for struct devres automatically, so size @new_size user request
+	 * is delivered to it directly as devm_kmalloc() does.
 	 */
 	new_dr = alloc_dr(devm_kmalloc_release,
-			  total_new_size, gfp, dev_to_node(dev));
+			  new_size, gfp, dev_to_node(dev));
 	if (!new_dr)
 		return NULL;
 
-- 
2.34.1