linux-kernel - [PATCH v2] staging: r8188eu: Use kzalloc() with GFP

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Date:   Mon,  1 Nov 2021 15:27:32 +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 v2] staging: r8188eu: Use kzalloc() with GFP_ATOMIC in  atomic context

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

This issue is detected by Smatch which emits the following warning:
"drivers/staging/r8188eu/core/rtw_mlme_ext.c:6848 report_del_sta_event()
warn: sleeping in atomic context".

After the change, the post-commit hook output the following message:
"CHECK: Prefer kzalloc(sizeof(*pcmd_obj)...) over
kzalloc(sizeof(struct cmd_obj)...)".

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

Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
---

v1->v2: Fix an overlooked error due to an incorrect copy-paste
	of the sizeof() operator.

 drivers/staging/r8188eu/core/rtw_mlme_ext.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/r8188eu/core/rtw_mlme_ext.c b/drivers/staging/r8188eu/core/rtw_mlme_ext.c
index 55c3d4a6faeb..315902682292 100644
--- a/drivers/staging/r8188eu/core/rtw_mlme_ext.c
+++ b/drivers/staging/r8188eu/core/rtw_mlme_ext.c
@@ -6845,12 +6845,12 @@ void report_del_sta_event(struct adapter *padapter, unsigned char *MacAddr, unsi
 	struct mlme_ext_priv		*pmlmeext = &padapter->mlmeextpriv;
 	struct cmd_priv *pcmdpriv = &padapter->cmdpriv;

-	pcmd_obj = kzalloc(sizeof(struct cmd_obj), GFP_KERNEL);
+	pcmd_obj = kzalloc(sizeof(*pcmd_obj), GFP_ATOMIC);
 	if (!pcmd_obj)
 		return;

 	cmdsz = (sizeof(struct stadel_event) + sizeof(struct C2HEvent_Header));
-	pevtcmd = kzalloc(cmdsz, GFP_KERNEL);
+	pevtcmd = kzalloc(cmdsz, GFP_ATOMIC);
 	if (!pevtcmd) {
 		kfree(pcmd_obj);
 		return;
-- 
2.33.1