From b57100a3d9ced8c2b78e87d313f514a3338d016e Mon Sep 17 00:00:00 2001 From: Malaya Kumar Rout Date: Tue, 14 Oct 2025 01:00:27 +0530 Subject: [PATCH] PM: console: Fix memory allocation error handling in pm_vt_switch_required() The pm_vt_switch_required() function fails silently when memory allocation fails, offering no indication to callers that the operation was unsuccessful. This behavior prevents drivers from handling allocation errors correctly or implementing retry mechanisms. By ensuring that failures are reported back to the caller, drivers can make informed decisions, improve robustness, and avoid unexpected behavior during critical power management operations. Change the function signature to return an integer error code and modify the implementation to return -ENOMEM when kmalloc() fails. Update both the function declaration and the inline stub in include/linux/pm.h to maintain consistency across CONFIG_VT_CONSOLE_SLEEP configurations. The function now returns: - 0 on success (including when updating existing entries) - -ENOMEM when memory allocation fails This change improves error reporting without breaking existing callers, as the current callers in drivers/video/fbdev/core/fbmem.c already ignore the return value, making this a backward-compatible improvement. Reviewed-by: Lyude Paul Signed-off-by: Malaya Kumar Rout Reviewed-by: Dhruva Gole Reviewed-by: Lyude Paul Link: https://patch.msgid.link/20251013193028.89570-1-mrout@redhat.com Signed-off-by: Rafael J. Wysocki --- include/linux/pm.h | 5 +++-- kernel/power/console.c | 8 ++++++-- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/include/linux/pm.h b/include/linux/pm.h index cc7b2dc28574c..a72e42eec1303 100644 --- a/include/linux/pm.h +++ b/include/linux/pm.h @@ -25,11 +25,12 @@ extern void (*pm_power_off)(void); struct device; /* we have a circular dep with device.h */ #ifdef CONFIG_VT_CONSOLE_SLEEP -extern void pm_vt_switch_required(struct device *dev, bool required); +extern int pm_vt_switch_required(struct device *dev, bool required); extern void pm_vt_switch_unregister(struct device *dev); #else -static inline void pm_vt_switch_required(struct device *dev, bool required) +static inline int pm_vt_switch_required(struct device *dev, bool required) { + return 0; } static inline void pm_vt_switch_unregister(struct device *dev) { diff --git a/kernel/power/console.c b/kernel/power/console.c index 19c48aa5355d2..a906a0ac0f9b9 100644 --- a/kernel/power/console.c +++ b/kernel/power/console.c @@ -44,9 +44,10 @@ static LIST_HEAD(pm_vt_switch_list); * no_console_suspend argument has been passed on the command line, VT * switches will occur. */ -void pm_vt_switch_required(struct device *dev, bool required) +int pm_vt_switch_required(struct device *dev, bool required) { struct pm_vt_switch *entry, *tmp; + int ret = 0; mutex_lock(&vt_switch_mutex); list_for_each_entry(tmp, &pm_vt_switch_list, head) { @@ -58,8 +59,10 @@ void pm_vt_switch_required(struct device *dev, bool required) } entry = kmalloc(sizeof(*entry), GFP_KERNEL); - if (!entry) + if (!entry) { + ret = -ENOMEM; goto out; + } entry->required = required; entry->dev = dev; @@ -67,6 +70,7 @@ void pm_vt_switch_required(struct device *dev, bool required) list_add(&entry->head, &pm_vt_switch_list); out: mutex_unlock(&vt_switch_mutex); + return ret; } EXPORT_SYMBOL(pm_vt_switch_required); -- 2.47.3