proc/kcore: replace kclist_lock rwlock with rwsem

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.

Link: http://lkml.kernel.org/r/521ba449ebe921d905177410fee9222d07882f0d.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 10 deletions

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index e83f15a4f66d..ae43a97d511d 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -59,7 +59,7 @@ struct memelfnote
 };
 
 static LIST_HEAD(kclist_head);
-static DEFINE_RWLOCK(kclist_lock);
+static DECLARE_RWSEM(kclist_lock);
 static int kcore_need_update = 1;
 
 /* This doesn't grab kclist_lock, so it should only be used at init time. */
@@ -117,7 +117,7 @@ static void __kcore_update_ram(struct list_head *list)
         struct kcore_list *tmp, *pos;
         LIST_HEAD(garbage);
 
-        write_lock(&kclist_lock);
+        down_write(&kclist_lock);
         if (xchg(&kcore_need_update, 0)) {
                 list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
                         if (pos->type == KCORE_RAM
@@ -128,7 +128,7 @@ static void __kcore_update_ram(struct list_head *list)
         } else
                 list_splice(list, &garbage);
         proc_root_kcore->size = get_kcore_size(&nphdr, &size);
-        write_unlock(&kclist_lock);
+        up_write(&kclist_lock);
 
         free_kclist_ents(&garbage);
 }
@@ -451,11 +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;
         }
 
@@ -472,11 +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;
@@ -491,7 +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
@@ -504,12 +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))