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Commit 7be48818 authored by Borislav Petkov's avatar Borislav Petkov Committed by Guenter Roeck
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hwmon: (fam15h_power) Disable preemption when reading registers 



We need to read a bunch of registers on each compute unit and possibly
on the current CPU too. Disable preemption around it. Otherwise, you
get:

  BUG: using smp_processor_id() in preemptible [00000000] code: systemd-udevd/327
  caller is read_registers+0x6a/0x110 [fam15h_power]
  CPU: 3 PID: 327 Comm: systemd-udevd Not tainted 4.7.0-rc1+ #4
  Hardware name: HP HP EliteBook 745 G3/807E, BIOS N73 Ver. 01.08 01/28/2016
  ...

Suggested-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Rui Huang <ray.huang@amd.com>
Cc: Sherry Hurwitz <sherry.hurwitz@amd.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Acked-by: default avatarHuang Rui <ray.huang@amd.com>
Tested-by: default avatarHuang Rui <ray.huang@amd.com>
Fixes: fa794344 ("hwmon: (fam15h_power) Add compute unit accumulated power")
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent af8c34ce

drivers/hwmon/fam15h_power.c

+2 −6
Original line number Diff line number Diff line
@@ -172,9 +172,9 @@ static void do_read_registers_on_cu(void *_data) 
 */

static int read_registers(struct fam15h_power_data *data)

{

	int this_cpu, ret, cpu;

	int core, this_core;

	cpumask_var_t mask;

	int ret, cpu;



	ret = zalloc_cpumask_var(&mask, GFP_KERNEL);

	if (!ret)
@@ -183,7 +183,6 @@ static int read_registers(struct fam15h_power_data *data) 
	memset(data->cu_on, 0, sizeof(int) * MAX_CUS);



	get_online_cpus();

	this_cpu = smp_processor_id();



	/*

	 * Choose the first online core of each compute unit, and then
@@ -205,12 +204,9 @@ static int read_registers(struct fam15h_power_data *data) 
		cpumask_set_cpu(cpumask_any(topology_sibling_cpumask(cpu)), mask);

	}



	if (cpumask_test_cpu(this_cpu, mask))

		do_read_registers_on_cu(data);

	on_each_cpu_mask(mask, do_read_registers_on_cu, data, true);



	smp_call_function_many(mask, do_read_registers_on_cu, data, true);

	put_online_cpus();



	free_cpumask_var(mask);



	return 0;