[PATCH v4] char/nvram: Remove redundant nvram_mutex

Venkat Rao Bagalkote
2026-03-30T10:35:53Z

The global nvram_mutex in drivers/char/nvram.c is redundant and unused,
and this triggers compiler warnings on some configurations.

All platform-specific nvram operations already provide their own internal
synchronization, meaning the wrapper-level mutex does not provide any
additional safety.

Remove the nvram_mutex definition along with all remaining lock/unlock
users across PPC32, x86, and m68k code paths, and rely entirely on the
per-architecture nvram implementations for locking.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
---
v4:
- Remove all remaining nvram_mutex call sites, completing the mutex removal

v3:
- Removed global nvram_mutex definition

drivers/char/nvram.c | 16 +++-------------
1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/drivers/char/nvram.c b/drivers/char/nvram.c
index 9eff426a9286..e89cc1f1c89e 100644
--- a/drivers/char/nvram.c
+++ b/drivers/char/nvram.c
@@ -53,7 +53,6 @@
#include <asm/nvram.h>
#endif

-static DEFINE_MUTEX(nvram_mutex);
static DEFINE_SPINLOCK(nvram_state_lock);
static int nvram_open_cnt; /* #times opened */
static int nvram_open_mode; /* special open modes */
@@ -310,11 +309,8 @@ static long nvram_misc_ioctl(struct file *file, unsigned int cmd,
break;
#ifdef CONFIG_PPC32
case IOC_NVRAM_SYNC:
- if (ppc_md.nvram_sync != NULL) {
- mutex_lock(&nvram_mutex);
+ if (ppc_md.nvram_sync)
ppc_md.nvram_sync();
- mutex_unlock(&nvram_mutex);
- }
ret = 0;
break;
#endif
@@ -324,11 +320,8 @@ static long nvram_misc_ioctl(struct file *file, unsigned int cmd,
if (!capable(CAP_SYS_ADMIN))
return -EACCES;

- if (arch_nvram_ops.initialize != NULL) {
- mutex_lock(&nvram_mutex);
+ if (arch_nvram_ops.initialize)
ret = arch_nvram_ops.initialize();
- mutex_unlock(&nvram_mutex);
- }
break;
case NVRAM_SETCKS:
/* just set checksum, contents unchanged (maybe useful after
@@ -336,11 +329,8 @@ static long nvram_misc_ioctl(struct file *file, unsigned int cmd,
if (!capable(CAP_SYS_ADMIN))
return -EACCES;

- if (arch_nvram_ops.set_checksum != NULL) {
- mutex_lock(&nvram_mutex);
+ if (arch_nvram_ops.set_checksum)
ret = arch_nvram_ops.set_checksum();
- mutex_unlock(&nvram_mutex);
- }
break;
#endif /* CONFIG_X86 || CONFIG_M68K */
}
--
2.45.2