linux-kernel - [PATCH v2 5/5] x86/mce/mce-inject: Return error code to userspace from mce-inject module

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Date:   Tue, 19 Oct 2021 18:36:41 -0500
From:   Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
To:     <x86@...nel.org>, <linux-edac@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     Tony Luck <tony.luck@...el.com>, "H . Peter Anvin" <hpa@...or.com>,
        <yazen.ghannam@....com>, <Smita.KoralahalliChannabasappa@....com>
Subject: [PATCH v2 5/5] x86/mce/mce-inject: Return error code to userspace from mce-inject module

Currently, the mce-inject module fails silently and user must look for
kernel logs to determine if the injection has succeeded.

Save time for the user and return error code from the module with
appropriate error statements if error injection fails.

Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
---
v2:
	Added pr_err() along with error code.
---
 arch/x86/kernel/cpu/mce/inject.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/inject.c b/arch/x86/kernel/cpu/mce/inject.c
index 72d29d26e033..a1c3c1e0425f 100644
--- a/arch/x86/kernel/cpu/mce/inject.c
+++ b/arch/x86/kernel/cpu/mce/inject.c
@@ -547,8 +547,11 @@ static void do_inject(void)
 	}
 
 	cpus_read_lock();
-	if (!cpu_online(cpu))
+	if (!cpu_online(cpu)) {
+		pr_err("No online CPUs available for error injection\n");
+		mce_err.err = -ENODEV;
 		goto err;
+	}
 
 	toggle_hw_mce_inject(cpu, true);
 
@@ -621,7 +624,7 @@ static int inj_bank_set(void *data, u64 val)
 	/* Reset injection struct */
 	setup_inj_struct(&i_mce);
 
-	return 0;
+	return mce_err.err;
 }
 
 MCE_INJECT_GET(bank);
-- 
2.17.1