linux-kernel - Re: [PATCH v1] mailbox: mchp-ipc-sbi: fix uninitialized symbol and other smatch warnings

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Message-ID: <aUPkF9XuB3sRy6JP@stanley.mountain>
Date: Thu, 18 Dec 2025 14:23:03 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Valentina Fernandez <valentina.fernandezalanis@...rochip.com>
Cc: jassisinghbrar@...il.com, conor.dooley@...rochip.com,
	linux-kernel@...r.kernel.org, lkp@...el.com
Subject: Re: [PATCH v1] mailbox: mchp-ipc-sbi: fix uninitialized symbol and
 other smatch warnings

On Thu, Dec 18, 2025 at 10:33:59AM +0000, Valentina Fernandez wrote:
> Fix uninitialized symbol 'hartid' warning in mchp_ipc_cluster_aggr_isr()
> by introducing a 'found' flag to track whether the IRQ matches any
> online hart. If no match is found, return IRQ_NONE.
> 
> Also fix other smatch warnings by removing dead code in
> mchp_ipc_startup() and by returning -ENODEV in dev_err_probe() if the
> Microchip SBI extension is not found.
> 
> Fixes below smatch warnings:
> drivers/mailbox/mailbox-mchp-ipc-sbi.c:187 mchp_ipc_cluster_aggr_isr() error: uninitialized symbol 'hartid'.
> drivers/mailbox/mailbox-mchp-ipc-sbi.c:324 mchp_ipc_startup() warn: ignoring unreachable code.
> drivers/mailbox/mailbox-mchp-ipc-sbi.c:422 mchp_ipc_probe() warn: passing zero to 'dev_err_probe'
> 
> Reported-by: kernel test robot <lkp@...el.com>
> Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> Closes: https://lore.kernel.org/r/202512171533.CDLdScMY-lkp@intel.com/
> Signed-off-by: Valentina Fernandez <valentina.fernandezalanis@...rochip.com>
> ---
>  drivers/mailbox/mailbox-mchp-ipc-sbi.c | 21 +++++++++------------
>  1 file changed, 9 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/mailbox/mailbox-mchp-ipc-sbi.c b/drivers/mailbox/mailbox-mchp-ipc-sbi.c
> index d444491a584e..b87bf2fb4b9b 100644
> --- a/drivers/mailbox/mailbox-mchp-ipc-sbi.c
> +++ b/drivers/mailbox/mailbox-mchp-ipc-sbi.c
> @@ -174,17 +174,21 @@ static irqreturn_t mchp_ipc_cluster_aggr_isr(int irq, void *data)
>  	struct mchp_ipc_msg ipc_msg;
>  	struct mchp_ipc_status status_msg;
>  	int ret;
> -	unsigned long hartid;
>  	u32 i, chan_index, chan_id;
> +	bool found = false;
>  
>  	/* Find out the hart that originated the irq */
>  	for_each_online_cpu(i) {
> -		hartid = cpuid_to_hartid_map(i);
> -		if (irq == ipc->cluster_cfg[i].irq)
> +		if (irq == ipc->cluster_cfg[i].irq) {
> +			found = true;
>  			break;
> +		}
>  	}
>  
> -	status_msg.cluster = hartid;
> +	if (unlikely(!found))
> +		return IRQ_NONE;

This one is a false positive because obviously there is going to be
at least one online cpu.  I would prefer to silence this in Smatch.
Generally, you should ignore static checker false positives.

regards,
dan carpenter

>From 3a2a0587208ca2f720cf170c1c9b84d155e87316 Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@...aro.org>
Date: Thu, 18 Dec 2025 14:17:36 +0300
Subject: [PATCH] kernel: add some more once_through macros

These macro loops always iterate at least once.

Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
---
 check_kernel.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/check_kernel.c b/check_kernel.c
index 0db972637aa2..03d1982db49c 100644
--- a/check_kernel.c
+++ b/check_kernel.c
@@ -765,7 +765,7 @@ static bool delete_pci_error_returns(struct expression *expr)
 	return false;
 }
 
-static bool match_with_intel_runtime(struct statement *stmt)
+static bool match_once_through_macros(struct statement *stmt)
 {
 	char *macro;
 
@@ -774,7 +774,10 @@ static bool match_with_intel_runtime(struct statement *stmt)
 		return false;
 	if (strncmp(macro, "with_intel_runtime", 18) == 0 ||
 	    strncmp(macro, "with_intel_display", 18) == 0 ||
-	    strcmp(macro, "drm_exec_until_all_locked") == 0)
+	    strcmp(macro, "drm_exec_until_all_locked") == 0 ||
+	    strcmp(macro, "xe_validation_guard") == 0 ||
+	    strcmp(macro, "for_each_gt") == 0 ||
+	    strcmp(macro, "for_each_online_cpu") ==0)
 		return true;
 	return false;
 }
@@ -821,7 +824,7 @@ void check_kernel(int id)
 	add_function_hook("closure_call", &match_closure_call, NULL);
 	add_function_hook("put_device", &match_put_device, NULL);
 
-	add_once_through_hook(&match_with_intel_runtime);
+	add_once_through_hook(&match_once_through_macros);
 
 	add_hook(fix_msecs_to_jiffies, ASSIGNMENT_HOOK_AFTER);
 	add_hook(&match_kernel_param, BASE_HOOK);
-- 
2.51.0