linux-kernel - [PATCH] staging: r8188eu: Use kzalloc() with GFP

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Date:   Sun,  6 Feb 2022 23:59:43 +0100
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Larry Finger <Larry.Finger@...inger.net>,
        Phillip Potter <phil@...lpotter.co.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Cc:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Subject: [PATCH] staging: r8188eu: Use kzalloc() with GFP_ATOMIC in atomic context

Use the GFP_ATOMIC flag of kzalloc() with two memory allocation in
rtw_set_key(). This function is called while holding spinlocks and with
disabled bottom halves, therefore it is not allowed to sleep. With the
GFP_ATOMIC type flag, the allocation is high priority and cannot sleep.

This issue is detected by Smatch which emits the following warning:
drivers/staging/r8188eu/core/rtw_pwrctrl.c:79 ips_leave() warn: sleeping in atomic context
drivers/staging/r8188eu/core/rtw_pwrctrl.c:81 ips_leave() warn: sleeping in atomic context

The calls chain (in reverse order) is the following:

rtw_set_key()
-> ips_leave()
-> -> rtw_pwr_wakeup()
-> -> -> rtw_set_802_11_disassociate()

The disabilitation of bottom halves and the acquisition of a spinlock is in
rtw_set_802_11_disassociate().

After the changes, the post-commit hook output the following messages:

CHECK: Prefer kzalloc(sizeof(*pcmd)...) over kzalloc(sizeof(struct cmd_obj)...)
+       pcmd = kzalloc(sizeof(struct cmd_obj), GFP_ATOMIC);

CHECK: Prefer kzalloc(sizeof(*psetkeyparm)...) over kzalloc(sizeof(struct setkey_parm)...)
+       psetkeyparm = kzalloc(sizeof(struct setkey_parm), GFP_ATOMIC).

According to the above "CHECK[S]", use the preferred style in the first
kzalloc().

Fixes: 79f712ea994d ("staging: r8188eu: Remove wrappers for kalloc() and kzalloc()")
Fixes: 15865124feed ("staging: r8188eu: introduce new core dir for RTL8188eu driver")
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
---
 drivers/staging/r8188eu/core/rtw_mlme.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/r8188eu/core/rtw_mlme.c b/drivers/staging/r8188eu/core/rtw_mlme.c
index 038bddc361c3..860835e29b79 100644
--- a/drivers/staging/r8188eu/core/rtw_mlme.c
+++ b/drivers/staging/r8188eu/core/rtw_mlme.c
@@ -1600,12 +1600,12 @@ int rtw_set_key(struct adapter *adapter, struct security_priv *psecuritypriv, in
 	struct mlme_priv		*pmlmepriv = &adapter->mlmepriv;
 	int	res = _SUCCESS;
 
-	pcmd = kzalloc(sizeof(struct cmd_obj), GFP_KERNEL);
+	pcmd = kzalloc(sizeof(*pcmd), GFP_ATOMIC);
 	if (!pcmd) {
 		res = _FAIL;  /* try again */
 		goto exit;
 	}
-	psetkeyparm = kzalloc(sizeof(struct setkey_parm), GFP_KERNEL);
+	psetkeyparm = kzalloc(sizeof(*psetkeyparm), GFP_ATOMIC);
 	if (!psetkeyparm) {
 		kfree(pcmd);
 		res = _FAIL;
-- 
2.34.1