From: Omar Sandoval <osan...@fb.com>
Now we only need kclist_lock from user context and at fs init time, and
the following changes need to sleep while holding the kclist_lock.
Signed-off-by: Omar Sandoval <osan...@fb.com>
---
fs/proc/kcore.c | 32 +++++++++++++++-----------------
1 file changed, 15 insertions(+), 17 deletions(-)
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index ddeeb3a5a015..def92fccb167 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -59,8 +59,8 @@ struct memelfnote
};
static LIST_HEAD(kclist_head);
-static DEFINE_RWLOCK(kclist_lock);
-static int kcore_need_update = 1;
+static DECLARE_RWSEM(kclist_lock);
+static atomic_t kcore_need_update = ATOMIC_INIT(1);
/* This doesn't grab kclist_lock, so it should only be used at init time. */
void
@@ -117,8 +117,8 @@ static void __kcore_update_ram(struct list_head *list)
struct kcore_list *tmp, *pos;
LIST_HEAD(garbage);
- write_lock(&kclist_lock);
- if (kcore_need_update) {
+ down_write(&kclist_lock);
+ if (atomic_cmpxchg(&kcore_need_update, 1, 0)) {
list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
if (pos->type == KCORE_RAM
|| pos->type == KCORE_VMEMMAP)
@@ -127,9 +127,8 @@ static void __kcore_update_ram(struct list_head *list)
list_splice_tail(list, &kclist_head);
} else
list_splice(list, &garbage);
- kcore_need_update = 0;
proc_root_kcore->size = get_kcore_size(&nphdr, &size);
- write_unlock(&kclist_lock);
+ up_write(&kclist_lock);
free_kclist_ents(&garbage);
}
@@ -452,11 +451,11 @@ read_kcore(struct file *file, char __user *buffer, size_t
buflen, loff_t *fpos)
int nphdr;
unsigned long start;
- read_lock(&kclist_lock);
+ down_read(&kclist_lock);
size = get_kcore_size(&nphdr, &elf_buflen);
if (buflen == 0 || *fpos >= size) {
- read_unlock(&kclist_lock);
+ up_read(&kclist_lock);
return 0;
}
@@ -473,11 +472,11 @@ read_kcore(struct file *file, char __user *buffer, size_t
buflen, loff_t *fpos)
tsz = buflen;
elf_buf = kzalloc(elf_buflen, GFP_ATOMIC);
if (!elf_buf) {
- read_unlock(&kclist_lock);
+ up_read(&kclist_lock);
return -ENOMEM;
}
elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
- read_unlock(&kclist_lock);
+ up_read(&kclist_lock);
if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
kfree(elf_buf);
return -EFAULT;
@@ -492,7 +491,7 @@ read_kcore(struct file *file, char __user *buffer, size_t
buflen, loff_t *fpos)
if (buflen == 0)
return acc;
} else
- read_unlock(&kclist_lock);
+ up_read(&kclist_lock);
/*
* Check to see if our file offset matches with any of
@@ -505,12 +504,12 @@ read_kcore(struct file *file, char __user *buffer, size_t
buflen, loff_t *fpos)
while (buflen) {
struct kcore_list *m;
- read_lock(&kclist_lock);
+ down_read(&kclist_lock);
list_for_each_entry(m, &kclist_head, list) {
if (start >= m->addr && start < (m->addr+m->size))
break;
}
- read_unlock(&kclist_lock);
+ up_read(&kclist_lock);
if (&m->list == &kclist_head) {
if (clear_user(buffer, tsz))
@@ -563,7 +562,7 @@ static int open_kcore(struct inode *inode, struct file
*filp)
if (!filp->private_data)
return -ENOMEM;
- if (kcore_need_update)
+ if (atomic_read(&kcore_need_update))
kcore_update_ram();
if (i_size_read(inode) != proc_root_kcore->size) {
inode_lock(inode);
@@ -593,9 +592,8 @@ static int __meminit kcore_callback(struct notifier_block
*self,
switch (action) {
case MEM_ONLINE:
case MEM_OFFLINE:
- write_lock(&kclist_lock);
- kcore_need_update = 1;
- write_unlock(&kclist_lock);
+ atomic_set(&kcore_need_update, 1);
+ break;
}
return NOTIFY_OK;
}
--
2.18.0
