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Subject[patch v2] LMB: Add basic spin locking to lmb
Add a spinlock to struct lmb to enforce concurrency in
lmb_add(), lmb_remove(), lmb_analyze(), lmb_find(), and
lmb_dump_all().

This locking is needed for SMP systems that access the lmb structure
during hot memory add and remove operations after secondary cpus
have been started.

Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
---
v2: o Add locking to lmb_find().

include/linux/lmb.h | 1
lib/lmb.c | 62 ++++++++++++++++++++++++++++++++++++++++------------
2 files changed, 49 insertions(+), 14 deletions(-)
--- a/include/linux/lmb.h
+++ b/include/linux/lmb.h
@@ -30,6 +30,7 @@ struct lmb_region {
};

struct lmb {
+ spinlock_t lock;
unsigned long debug;
u64 rmo_size;
struct lmb_region memory;
--- a/lib/lmb.c
+++ b/lib/lmb.c
@@ -32,28 +32,33 @@ early_param("lmb", early_lmb);
void lmb_dump_all(void)
{
unsigned long i;
+ struct lmb tmp;

if (!lmb_debug)
return;

+ spin_lock(&lmb.lock);
+ tmp = lmb;
+ spin_unlock(&lmb.lock);
+
pr_info("lmb_dump_all:\n");
- pr_info(" memory.cnt = 0x%lx\n", lmb.memory.cnt);
+ pr_info(" memory.cnt = 0x%lx\n", tmp.memory.cnt);
pr_info(" memory.size = 0x%llx\n",
- (unsigned long long)lmb.memory.size);
- for (i=0; i < lmb.memory.cnt ;i++) {
+ (unsigned long long)tmp.memory.size);
+ for (i=0; i < tmp.memory.cnt ;i++) {
pr_info(" memory.region[0x%lx].base = 0x%llx\n",
- i, (unsigned long long)lmb.memory.region[i].base);
+ i, (unsigned long long)tmp.memory.region[i].base);
pr_info(" .size = 0x%llx\n",
- (unsigned long long)lmb.memory.region[i].size);
+ (unsigned long long)tmp.memory.region[i].size);
}

- pr_info(" reserved.cnt = 0x%lx\n", lmb.reserved.cnt);
- pr_info(" reserved.size = 0x%lx\n", lmb.reserved.size);
- for (i=0; i < lmb.reserved.cnt ;i++) {
+ pr_info(" reserved.cnt = 0x%lx\n", tmp.reserved.cnt);
+ pr_info(" reserved.size = 0x%lx\n", tmp.reserved.size);
+ for (i=0; i < tmp.reserved.cnt ;i++) {
pr_info(" reserved.region[0x%lx].base = 0x%llx\n",
- i, (unsigned long long)lmb.reserved.region[i].base);
+ i, (unsigned long long)tmp.reserved.region[i].base);
pr_info(" .size = 0x%llx\n",
- (unsigned long long)lmb.reserved.region[i].size);
+ (unsigned long long)tmp.reserved.region[i].size);
}
}

@@ -105,6 +110,8 @@ static void lmb_coalesce_regions(struct

void __init lmb_init(void)
{
+ spin_lock_init(&lmb.lock);
+
/* Create a dummy zero size LMB which will get coalesced away later.
* This simplifies the lmb_add() code below...
*/
@@ -122,10 +129,14 @@ void __init lmb_analyze(void)
{
int i;

+ spin_lock(&lmb.lock);
+
lmb.memory.size = 0;

for (i = 0; i < lmb.memory.cnt; i++)
lmb.memory.size += lmb.memory.region[i].size;
+
+ spin_unlock(&lmb.lock);
}

static long lmb_add_region(struct lmb_region *rgn, u64 base, u64 size)
@@ -194,18 +205,25 @@ static long lmb_add_region(struct lmb_re

long lmb_add(u64 base, u64 size)
{
+ long ret;
struct lmb_region *_rgn = &lmb.memory;

+ spin_lock(&lmb.lock);
+
/* On pSeries LPAR systems, the first LMB is our RMO region. */
if (base == 0)
lmb.rmo_size = size;

- return lmb_add_region(_rgn, base, size);
+ ret = lmb_add_region(_rgn, base, size);
+
+ spin_unlock(&lmb.lock);
+ return ret;

}

long lmb_remove(u64 base, u64 size)
{
+ long ret;
struct lmb_region *rgn = &(lmb.memory);
u64 rgnbegin, rgnend;
u64 end = base + size;
@@ -213,6 +231,8 @@ long lmb_remove(u64 base, u64 size)

rgnbegin = rgnend = 0; /* supress gcc warnings */

+ spin_lock(&lmb.lock);
+
/* Find the region where (base, size) belongs to */
for (i=0; i < rgn->cnt; i++) {
rgnbegin = rgn->region[i].base;
@@ -223,12 +243,15 @@ long lmb_remove(u64 base, u64 size)
}

/* Didn't find the region */
- if (i == rgn->cnt)
+ if (i == rgn->cnt) {
+ spin_unlock(&lmb.lock);
return -1;
+ }

/* Check to see if we are removing entire region */
if ((rgnbegin == base) && (rgnend == end)) {
lmb_remove_region(rgn, i);
+ spin_unlock(&lmb.lock);
return 0;
}

@@ -236,12 +259,14 @@ long lmb_remove(u64 base, u64 size)
if (rgnbegin == base) {
rgn->region[i].base = end;
rgn->region[i].size -= size;
+ spin_unlock(&lmb.lock);
return 0;
}

/* Check to see if the region is matching at the end */
if (rgnend == end) {
rgn->region[i].size -= size;
+ spin_unlock(&lmb.lock);
return 0;
}

@@ -250,7 +275,10 @@ long lmb_remove(u64 base, u64 size)
* beginging of the hole and add the region after hole.
*/
rgn->region[i].size = base - rgn->region[i].base;
- return lmb_add_region(rgn, end, rgnend - end);
+ ret = lmb_add_region(rgn, end, rgnend - end);
+
+ spin_unlock(&lmb.lock);
+ return ret;
}

long __init lmb_reserve(u64 base, u64 size)
@@ -502,12 +530,16 @@ int lmb_find(struct lmb_property *res)
rstart = res->base;
rend = rstart + res->size - 1;

+ spin_lock(&lmb.lock);
+
for (i = 0; i < lmb.memory.cnt; i++) {
u64 start = lmb.memory.region[i].base;
u64 end = start + lmb.memory.region[i].size - 1;

- if (start > rend)
+ if (start > rend) {
+ spin_unlock(&lmb.lock);
return -1;
+ }

if ((end >= rstart) && (start < rend)) {
/* adjust the request */
@@ -517,8 +549,10 @@ int lmb_find(struct lmb_property *res)
rend = end;
res->base = rstart;
res->size = rend - rstart + 1;
+ spin_unlock(&lmb.lock);
return 0;
}
}
+ spin_unlock(&lmb.lock);
return -1;
}



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