Home Home > GIT Browse
summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2019-06-16 07:19:15 -1000
committerLinus Torvalds <torvalds@linux-foundation.org>2019-06-16 07:19:15 -1000
commitf763cf8e47d3aa4b081e0537d060c12818de8d0f (patch)
tree645ef0a0ee8b96ebfbec348742b1311ba29ce931
parente01e060fe00dca46959bbf055b75d9f57ba6e7be (diff)
parent0ade0b6240c4853cf9725924c46c10f4251639d7 (diff)
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
-rw-r--r--drivers/ras/cec.c80
1 files changed, 42 insertions, 38 deletions
diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c
index 88e4f3ff0cb8..673f8a128397 100644
--- a/drivers/ras/cec.c
+++ b/drivers/ras/cec.c
@@ -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");
}