Commit 80347cd5 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Borislav Petkov (AMD)
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x86/microcode: Remove microcode_mutex 



microcode_mutex is only used by reload_store(). It has a comment saying
"to synchronize with each other". Other user of this mutex have been
removed in the commits

  181b6f40 ("x86/microcode: Rip out the OLD_INTERFACE").
  b6f86689 ("x86/microcode: Rip out the subsys interface gunk")

The sysfs interface does not need additional synchronisation vs itself
because it is provided as kernfs_ops::mutex which is acquired in
kernfs_fop_write_iter().

Remove the superfluous microcode_mutex.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarSohil Mehta <sohil.mehta@intel.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230804075853.JF_n6GXC@linutronix.de
parent 05e91e72

arch/x86/kernel/cpu/common.c

+1 −2
Original line number Diff line number Diff line
@@ -2276,8 +2276,7 @@ void store_cpu_caps(struct cpuinfo_x86 *curr_info) 
 * @prev_info:	CPU capabilities stored before an update.

 *

 * The microcode loader calls this upon late microcode load to recheck features,

 * only when microcode has been updated. Caller holds microcode_mutex and CPU

 * hotplug lock.

 * only when microcode has been updated. Caller holds and CPU hotplug lock.

 *

 * Return: None

 */

arch/x86/kernel/cpu/microcode/core.c

+0 −6
Original line number Diff line number Diff line
@@ -54,15 +54,12 @@ LIST_HEAD(microcode_cache); 
 *

 * All non cpu-hotplug-callback call sites use:

 *

 * - microcode_mutex to synchronize with each other;

 * - cpus_read_lock/unlock() to synchronize with

 *   the cpu-hotplug-callback call sites.

 *

 * We guarantee that only a single cpu is being

 * updated at any particular moment of time.

 */

static DEFINE_MUTEX(microcode_mutex);



struct ucode_cpu_info		ucode_cpu_info[NR_CPUS];



struct cpu_info_ctx {
@@ -488,10 +485,7 @@ static ssize_t reload_store(struct device *dev, 
	if (tmp_ret != UCODE_NEW)

		goto put;



	mutex_lock(&microcode_mutex);

	ret = microcode_reload_late();

	mutex_unlock(&microcode_mutex);



put:

	cpus_read_unlock();