[PATCH] netconsole: Fix compiler warnings when PRINTK_EXECUTION_CTX is disabled

[PATCH] netconsole: Fix compiler warnings when PRINTK_EXECUTION_CTX is disabled

[Chelsy Ratnawat]

The netconsole change that started using nbcon_write_context for CPU
and task information assumes CONFIG_PRINTK_EXECUTION_CTX is enabled.

However, when this option is disabled, struct nbcon_write_context does
not contain the cpu and comm fields, causing compilation failures:

  error: 'struct nbcon_write_context' has no member named 'cpu'
  error: 'struct nbcon_write_context' has no member named 'comm'

Guard access to these fields and fall back to raw_smp_processor_id()
and current->comm when PRINTK_EXECUTION_CTX is disabled.

Fixes: 79ba362b4337 ("netconsole: Use printk context for CPU and task information")
Signed-off-by: Chelsy Ratnawat <chelsyratnawat2001@gmail.com>
---
 drivers/net/netconsole.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 3c9acd6e49e8..bbd39b2e7a36 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -1494,17 +1494,30 @@ static void populate_configfs_item(struct netconsole_target *nt,
 static int sysdata_append_cpu_nr(struct netconsole_target *nt, int offset,
 				 struct nbcon_write_context *wctxt)
 {
+	int cpu;
+#ifdef CONFIG_PRINTK_EXECUTION_CTX
+	cpu = wctxt->cpu;
+#else
+	cpu = raw_smp_processor_id();
+#endif
+
 	return scnprintf(&nt->sysdata[offset],
 			 MAX_EXTRADATA_ENTRY_LEN, " cpu=%u\n",
-			 wctxt->cpu);
+			 cpu);
 }
 
 static int sysdata_append_taskname(struct netconsole_target *nt, int offset,
 				   struct nbcon_write_context *wctxt)
 {
+	const char *comm;
+#ifdef CONFIG_PRINTK_EXECUTION_CTX
+	comm = wctxt->comm;
+#else
+	comm = current->comm;
+#endif
 	return scnprintf(&nt->sysdata[offset],
 			 MAX_EXTRADATA_ENTRY_LEN, " taskname=%s\n",
-			 wctxt->comm);
+			 comm);
 }
 
 static int sysdata_append_release(struct netconsole_target *nt, int offset)
-- 
2.47.3

Re: [PATCH] netconsole: Fix compiler warnings when PRINTK_EXECUTION_CTX is disabled

[Breno Leitao]

Hello Chelsy,

On Mon, Mar 09, 2026 at 05:12:33AM -0700, Chelsy Ratnawat wrote:
> The netconsole change that started using nbcon_write_context for CPU
> and task information assumes CONFIG_PRINTK_EXECUTION_CTX is enabled.

in fact, NETCONSOLE_DYNAMIC selects CONFIG_PRINTK_EXECUTION_CTX. In
other words, were you able to get NETCONSOLE_DYNAMIC without having
CONFIG_PRINTK_EXECUTION_CTX set?

> However, when this option is disabled, struct nbcon_write_context does
> not contain the cpu and comm fields, causing compilation failures:
> 
>   error: 'struct nbcon_write_context' has no member named 'cpu'
>   error: 'struct nbcon_write_context' has no member named 'comm'
> 
> Guard access to these fields and fall back to raw_smp_processor_id()
> and current->comm when PRINTK_EXECUTION_CTX is disabled.

Please don't do it. We want to disable NETCONSOLE_DYNAMIC to be enabled
(thus, not using ->cpu and ->comm) if CONFIG_PRINTK_EXECUTION_CTX is not
set.

Thanks for the report,
--breno