[PATCH v3 6/6] x86/mce/mce-inject: Return error code to userspace from mce-inject module

[Smita Koralahalli]

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@xxxxxxx>
Link: https://lkml.kernel.org/r/20211019233641.140275-6-Smita.KoralahalliChannabasappa@xxxxxxx
---
v2:
	Added pr_err() along with error code.
v3:
	Rephrased the statement: No online CPUs available for error
	injection -> Chosen CPU is not online.
---
 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 d4e6d753018f..09f46d213cf5 100644
--- a/arch/x86/kernel/cpu/mce/inject.c
+++ b/arch/x86/kernel/cpu/mce/inject.c
@@ -569,8 +569,11 @@ static void do_inject(void)
 	}
 
 	cpus_read_lock();
-	if (!cpu_online(cpu))
+	if (!cpu_online(cpu)) {
+		pr_err("Chosen CPU is not online\n");
+		mce_err.err = -ENODEV;
 		goto err;
+	}
 
 	toggle_hw_mce_inject(cpu, true);
 
@@ -653,7 +656,7 @@ 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