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Merge branch 'ras-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull RAS fixes from Thomas Gleixner:
 "Two small fixes for RAS:

   - Use a proper search algorithm to find the correct element in the
     CEC array. The replacement was a better choice than fixing the
     crash causes by the original search function with horrible duct
     tape.

   - Move the timer based decay function into thread context so it can
     actually acquire the mutex which protects the CEC array to prevent
     corruption"

* 'ras-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  RAS/CEC: Convert the timer callback to a workqueue
  RAS/CEC: Fix binary search function
This commit is contained in:
Linus Torvalds 2019-06-16 07:19:15 -10:00
parent e01e060fe0 0ade0b6240
commit f763cf8e47
1 changed files with 42 additions and 38 deletions
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80
drivers/ras/cec.c
View File

@ -2,6 +2,7 @@
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/workqueue.h>
#include <asm/mce.h>
@ -123,16 +124,12 @@ static u64 dfs_pfn;
/* Amount of errors after which we offline */
static unsigned int count_threshold = COUNT_MASK;
/*
* The timer "decays" element count each timer_interval which is 24hrs by
* default.
*/
#define CEC_TIMER_DEFAULT_INTERVAL 24 * 60 * 60 /* 24 hrs */
#define CEC_TIMER_MIN_INTERVAL 1 * 60 * 60 /* 1h */
#define CEC_TIMER_MAX_INTERVAL 30 * 24 * 60 * 60 /* one month */
static struct timer_list cec_timer;
static u64 timer_interval = CEC_TIMER_DEFAULT_INTERVAL;
/* Each element "decays" each decay_interval which is 24hrs by default. */
#define CEC_DECAY_DEFAULT_INTERVAL 24 * 60 * 60 /* 24 hrs */
#define CEC_DECAY_MIN_INTERVAL 1 * 60 * 60 /* 1h */
#define CEC_DECAY_MAX_INTERVAL 30 * 24 * 60 * 60 /* one month */
static struct delayed_work cec_work;
static u64 decay_interval = CEC_DECAY_DEFAULT_INTERVAL;
/*
* Decrement decay value. We're using DECAY_BITS bits to denote decay of an
@ -160,20 +157,21 @@ static void do_spring_cleaning(struct ce_array *ca)
/*
* @interval in seconds
*/
static void cec_mod_timer(struct timer_list *t, unsigned long interval)
static void cec_mod_work(unsigned long interval)
{
unsigned long iv;
iv = interval * HZ + jiffies;
mod_timer(t, round_jiffies(iv));
iv = interval * HZ;
mod_delayed_work(system_wq, &cec_work, round_jiffies(iv));
}
static void cec_timer_fn(struct timer_list *unused)
static void cec_work_fn(struct work_struct *work)
{
mutex_lock(&ce_mutex);
do_spring_cleaning(&ce_arr);
mutex_unlock(&ce_mutex);
cec_mod_timer(&cec_timer, timer_interval);
cec_mod_work(decay_interval);
}
/*
@ -183,32 +181,38 @@ static void cec_timer_fn(struct timer_list *unused)
*/
static int __find_elem(struct ce_array *ca, u64 pfn, unsigned int *to)
{
int min = 0, max = ca->n - 1;
u64 this_pfn;
int min = 0, max = ca->n;
while (min < max) {
int tmp = (max + min) >> 1;
while (min <= max) {
int i = (min + max) >> 1;
this_pfn = PFN(ca->array[tmp]);
this_pfn = PFN(ca->array[i]);
if (this_pfn < pfn)
min = tmp + 1;
min = i + 1;
else if (this_pfn > pfn)
max = tmp;
else {
min = tmp;
break;
max = i - 1;
else if (this_pfn == pfn) {
if (to)
*to = i;
return i;
}
}
/*
* When the loop terminates without finding @pfn, min has the index of
* the element slot where the new @pfn should be inserted. The loop
* terminates when min > max, which means the min index points to the
* bigger element while the max index to the smaller element, in-between
* which the new @pfn belongs to.
*
* For more details, see exercise 1, Section 6.2.1 in TAOCP, vol. 3.
*/
if (to)
*to = min;
this_pfn = PFN(ca->array[min]);
if (this_pfn == pfn)
return min;
return -ENOKEY;
}
@ -374,15 +378,15 @@ static int decay_interval_set(void *data, u64 val)
{
*(u64 *)data = val;
if (val < CEC_TIMER_MIN_INTERVAL)
if (val < CEC_DECAY_MIN_INTERVAL)
return -EINVAL;
if (val > CEC_TIMER_MAX_INTERVAL)
if (val > CEC_DECAY_MAX_INTERVAL)
return -EINVAL;
timer_interval = val;
decay_interval = val;
cec_mod_timer(&cec_timer, timer_interval);
cec_mod_work(decay_interval);
return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(decay_interval_ops, u64_get, decay_interval_set, "%lld\n");
@ -426,7 +430,7 @@ static int array_dump(struct seq_file *m, void *v)
seq_printf(m, "Flags: 0x%x\n", ca->flags);
seq_printf(m, "Timer interval: %lld seconds\n", timer_interval);
seq_printf(m, "Decay interval: %lld seconds\n", decay_interval);
seq_printf(m, "Decays: %lld\n", ca->decays_done);
seq_printf(m, "Action threshold: %d\n", count_threshold);
@ -472,7 +476,7 @@ static int __init create_debugfs_nodes(void)
}
decay = debugfs_create_file("decay_interval", S_IRUSR | S_IWUSR, d,
&timer_interval, &decay_interval_ops);
&decay_interval, &decay_interval_ops);
if (!decay) {
pr_warn("Error creating decay_interval debugfs node!\n");
goto err;
@ -508,8 +512,8 @@ void __init cec_init(void)
if (create_debugfs_nodes())
return;
timer_setup(&cec_timer, cec_timer_fn, 0);
cec_mod_timer(&cec_timer, CEC_TIMER_DEFAULT_INTERVAL);
INIT_DELAYED_WORK(&cec_work, cec_work_fn);
schedule_delayed_work(&cec_work, CEC_DECAY_DEFAULT_INTERVAL);
pr_info("Correctable Errors collector initialized.\n");
}