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Diffstat (limited to 'fs/proc/vmcore.c')
-rw-r--r--fs/proc/vmcore.c41
1 files changed, 22 insertions, 19 deletions
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 702754dd1daf..edeb01dfe05d 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -62,7 +62,8 @@ core_param(novmcoredd, vmcoredd_disabled, bool, 0);
/* Device Dump Size */
static size_t vmcoredd_orig_sz;
-static DECLARE_RWSEM(vmcore_cb_rwsem);
+static DEFINE_SPINLOCK(vmcore_cb_lock);
+DEFINE_STATIC_SRCU(vmcore_cb_srcu);
/* List of registered vmcore callbacks. */
static LIST_HEAD(vmcore_cb_list);
/* Whether the vmcore has been opened once. */
@@ -70,8 +71,8 @@ static bool vmcore_opened;
void register_vmcore_cb(struct vmcore_cb *cb)
{
- down_write(&vmcore_cb_rwsem);
INIT_LIST_HEAD(&cb->next);
+ spin_lock(&vmcore_cb_lock);
list_add_tail(&cb->next, &vmcore_cb_list);
/*
* Registering a vmcore callback after the vmcore was opened is
@@ -79,14 +80,14 @@ void register_vmcore_cb(struct vmcore_cb *cb)
*/
if (vmcore_opened)
pr_warn_once("Unexpected vmcore callback registration\n");
- up_write(&vmcore_cb_rwsem);
+ spin_unlock(&vmcore_cb_lock);
}
EXPORT_SYMBOL_GPL(register_vmcore_cb);
void unregister_vmcore_cb(struct vmcore_cb *cb)
{
- down_write(&vmcore_cb_rwsem);
- list_del(&cb->next);
+ spin_lock(&vmcore_cb_lock);
+ list_del_rcu(&cb->next);
/*
* Unregistering a vmcore callback after the vmcore was opened is
* very unusual (e.g., forced driver removal), but we cannot stop
@@ -94,7 +95,9 @@ void unregister_vmcore_cb(struct vmcore_cb *cb)
*/
if (vmcore_opened)
pr_warn_once("Unexpected vmcore callback unregistration\n");
- up_write(&vmcore_cb_rwsem);
+ spin_unlock(&vmcore_cb_lock);
+
+ synchronize_srcu(&vmcore_cb_srcu);
}
EXPORT_SYMBOL_GPL(unregister_vmcore_cb);
@@ -103,9 +106,8 @@ static bool pfn_is_ram(unsigned long pfn)
struct vmcore_cb *cb;
bool ret = true;
- lockdep_assert_held_read(&vmcore_cb_rwsem);
-
- list_for_each_entry(cb, &vmcore_cb_list, next) {
+ list_for_each_entry_srcu(cb, &vmcore_cb_list, next,
+ srcu_read_lock_held(&vmcore_cb_srcu)) {
if (unlikely(!cb->pfn_is_ram))
continue;
ret = cb->pfn_is_ram(cb, pfn);
@@ -118,9 +120,9 @@ static bool pfn_is_ram(unsigned long pfn)
static int open_vmcore(struct inode *inode, struct file *file)
{
- down_read(&vmcore_cb_rwsem);
+ spin_lock(&vmcore_cb_lock);
vmcore_opened = true;
- up_read(&vmcore_cb_rwsem);
+ spin_unlock(&vmcore_cb_lock);
return 0;
}
@@ -133,6 +135,7 @@ ssize_t read_from_oldmem(char *buf, size_t count,
unsigned long pfn, offset;
size_t nr_bytes;
ssize_t read = 0, tmp;
+ int idx;
if (!count)
return 0;
@@ -140,7 +143,7 @@ ssize_t read_from_oldmem(char *buf, size_t count,
offset = (unsigned long)(*ppos % PAGE_SIZE);
pfn = (unsigned long)(*ppos / PAGE_SIZE);
- down_read(&vmcore_cb_rwsem);
+ idx = srcu_read_lock(&vmcore_cb_srcu);
do {
if (count > (PAGE_SIZE - offset))
nr_bytes = PAGE_SIZE - offset;
@@ -165,7 +168,7 @@ ssize_t read_from_oldmem(char *buf, size_t count,
offset, userbuf);
}
if (tmp < 0) {
- up_read(&vmcore_cb_rwsem);
+ srcu_read_unlock(&vmcore_cb_srcu, idx);
return tmp;
}
@@ -176,8 +179,8 @@ ssize_t read_from_oldmem(char *buf, size_t count,
++pfn;
offset = 0;
} while (count);
+ srcu_read_unlock(&vmcore_cb_srcu, idx);
- up_read(&vmcore_cb_rwsem);
return read;
}
@@ -568,18 +571,18 @@ static int vmcore_remap_oldmem_pfn(struct vm_area_struct *vma,
unsigned long from, unsigned long pfn,
unsigned long size, pgprot_t prot)
{
- int ret;
+ int ret, idx;
/*
- * Check if oldmem_pfn_is_ram was registered to avoid
- * looping over all pages without a reason.
+ * Check if a callback was registered to avoid looping over all
+ * pages without a reason.
*/
- down_read(&vmcore_cb_rwsem);
+ idx = srcu_read_lock(&vmcore_cb_srcu);
if (!list_empty(&vmcore_cb_list))
ret = remap_oldmem_pfn_checked(vma, from, pfn, size, prot);
else
ret = remap_oldmem_pfn_range(vma, from, pfn, size, prot);
- up_read(&vmcore_cb_rwsem);
+ srcu_read_unlock(&vmcore_cb_srcu, idx);
return ret;
}