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From:   Geert Uytterhoeven <geert+renesas@glider.be>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Dan Carpenter <dan.carpenter@linaro.org>
Cc:     linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org,
        Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH] lib: dhry: Fix sleeping allocations inside non-preemptable section
Date:   Wed,  5 Jul 2023 16:54:04 +0200
Message-Id: <bac6d517818a7cd8efe217c1ad649fffab9cc371.1688568764.git.geert+renesas@glider.be>
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The Smatch static checker reports the following warnings:

    lib/dhry_run.c:38 dhry_benchmark() warn: sleeping in atomic context
    lib/dhry_run.c:43 dhry_benchmark() warn: sleeping in atomic context

Indeed, dhry() does sleeping allocations inside the non-preemptable
section delimited by get_cpu()/put_cpu().

Fix this by using atomic allocations instead.
Add error handling, as atomic these allocations may fail.

Fixes: 13684e966d46283e ("lib: dhry: fix unstable smp_processor_id(_) usage")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/0469eb3a-02eb-4b41-b189-de20b931fa56@moroto.mountain
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Alternatively, memory (de)allocation could be spin off into their own
functions, and called outside the non-preemptable section.  But that
would be more intrusive.
---
 lib/dhry_1.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/lib/dhry_1.c b/lib/dhry_1.c
index 83247106824cc7f4..08edbbb19f573ff7 100644
--- a/lib/dhry_1.c
+++ b/lib/dhry_1.c
@@ -139,8 +139,15 @@ int dhry(int n)
 
 	/* Initializations */
 
-	Next_Ptr_Glob = (Rec_Pointer)kzalloc(sizeof(Rec_Type), GFP_KERNEL);
-	Ptr_Glob = (Rec_Pointer)kzalloc(sizeof(Rec_Type), GFP_KERNEL);
+	Next_Ptr_Glob = (Rec_Pointer)kzalloc(sizeof(Rec_Type), GFP_ATOMIC);
+	if (!Next_Ptr_Glob)
+		return -ENOMEM;
+
+	Ptr_Glob = (Rec_Pointer)kzalloc(sizeof(Rec_Type), GFP_ATOMIC);
+	if (!Ptr_Glob) {
+		kfree(Next_Ptr_Glob);
+		return -ENOMEM;
+	}
 
 	Ptr_Glob->Ptr_Comp = Next_Ptr_Glob;
 	Ptr_Glob->Discr = Ident_1;
-- 
2.34.1