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firmware/br-ext-chip-allwinner/board/v83x/kernel/patches/00000-fs_debugfs_file.c.patch

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diff -drupN a/fs/debugfs/file.c b/fs/debugfs/file.c
--- a/fs/debugfs/file.c 2018-08-06 17:23:04.000000000 +0300
+++ b/fs/debugfs/file.c 2022-06-12 05:28:14.000000000 +0300
@@ -9,7 +9,7 @@
* 2 as published by the Free Software Foundation.
*
* debugfs is for people to use instead of /proc or /sys.
- * See Documentation/DocBook/filesystems for more details.
+ * See Documentation/filesystems/ for more details.
*
*/
@@ -22,7 +22,6 @@
#include <linux/slab.h>
#include <linux/atomic.h>
#include <linux/device.h>
-#include <linux/srcu.h>
#include <asm/poll.h>
#include "internal.h"
@@ -48,66 +47,76 @@ const struct file_operations debugfs_noo
.llseek = noop_llseek,
};
+#define F_DENTRY(filp) ((filp)->f_path.dentry)
+
+const struct file_operations *debugfs_real_fops(const struct file *filp)
+ __must_hold(&debugfs_srcu)
+{
+ struct debugfs_fsdata *fsd = F_DENTRY(filp)->d_fsdata;
+ /*
+ * Neither the pointer to the struct file_operations, nor its
+ * contents ever change -- srcu_dereference() is not needed here.
+ */
+ return fsd->real_fops;
+}
+EXPORT_SYMBOL_GPL(debugfs_real_fops);
+
/**
- * debugfs_use_file_start - mark the beginning of file data access
+ * debugfs_file_get - mark the beginning of file data access
* @dentry: the dentry object whose data is being accessed.
- * @srcu_idx: a pointer to some memory to store a SRCU index in.
*
- * Up to a matching call to debugfs_use_file_finish(), any
- * successive call into the file removing functions debugfs_remove()
- * and debugfs_remove_recursive() will block. Since associated private
+ * Up to a matching call to debugfs_file_put(), any successive call
+ * into the file removing functions debugfs_remove() and
+ * debugfs_remove_recursive() will block. Since associated private
* file data may only get freed after a successful return of any of
* the removal functions, you may safely access it after a successful
- * call to debugfs_use_file_start() without worrying about
- * lifetime issues.
+ * call to debugfs_file_get() without worrying about lifetime issues.
*
* If -%EIO is returned, the file has already been removed and thus,
* it is not safe to access any of its data. If, on the other hand,
* it is allowed to access the file data, zero is returned.
- *
- * Regardless of the return code, any call to
- * debugfs_use_file_start() must be followed by a matching call
- * to debugfs_use_file_finish().
*/
-int debugfs_use_file_start(const struct dentry *dentry, int *srcu_idx)
- __acquires(&debugfs_srcu)
+int debugfs_file_get(struct dentry *dentry)
{
- *srcu_idx = srcu_read_lock(&debugfs_srcu);
- barrier();
+ struct debugfs_fsdata *fsd = dentry->d_fsdata;
+
+ /* Avoid starvation of removers. */
if (d_unlinked(dentry))
return -EIO;
+
+ if (!refcount_inc_not_zero(&fsd->active_users))
+ return -EIO;
+
return 0;
}
-EXPORT_SYMBOL_GPL(debugfs_use_file_start);
+EXPORT_SYMBOL_GPL(debugfs_file_get);
/**
- * debugfs_use_file_finish - mark the end of file data access
- * @srcu_idx: the SRCU index "created" by a former call to
- * debugfs_use_file_start().
+ * debugfs_file_put - mark the end of file data access
+ * @dentry: the dentry object formerly passed to
+ * debugfs_file_get().
*
* Allow any ongoing concurrent call into debugfs_remove() or
* debugfs_remove_recursive() blocked by a former call to
- * debugfs_use_file_start() to proceed and return to its caller.
+ * debugfs_file_get() to proceed and return to its caller.
*/
-void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu)
+void debugfs_file_put(struct dentry *dentry)
{
- srcu_read_unlock(&debugfs_srcu, srcu_idx);
-}
-EXPORT_SYMBOL_GPL(debugfs_use_file_finish);
+ struct debugfs_fsdata *fsd = dentry->d_fsdata;
-#define F_DENTRY(filp) ((filp)->f_path.dentry)
+ if (refcount_dec_and_test(&fsd->active_users))
+ complete(&fsd->active_users_drained);
+}
+EXPORT_SYMBOL_GPL(debugfs_file_put);
static int open_proxy_open(struct inode *inode, struct file *filp)
{
- const struct dentry *dentry = F_DENTRY(filp);
+ struct dentry *dentry = F_DENTRY(filp);
const struct file_operations *real_fops = NULL;
- int srcu_idx, r;
+ int r = 0;
- r = debugfs_use_file_start(dentry, &srcu_idx);
- if (r) {
- r = -ENOENT;
- goto out;
- }
+ if (debugfs_file_get(dentry))
+ return -ENOENT;
real_fops = debugfs_real_fops(filp);
real_fops = fops_get(real_fops);
@@ -124,7 +133,7 @@ static int open_proxy_open(struct inode
r = real_fops->open(inode, filp);
out:
- debugfs_use_file_finish(srcu_idx);
+ debugfs_file_put(dentry);
return r;
}
@@ -138,16 +147,16 @@ const struct file_operations debugfs_ope
#define FULL_PROXY_FUNC(name, ret_type, filp, proto, args) \
static ret_type full_proxy_ ## name(proto) \
{ \
- const struct dentry *dentry = F_DENTRY(filp); \
+ struct dentry *dentry = F_DENTRY(filp); \
const struct file_operations *real_fops = \
debugfs_real_fops(filp); \
- int srcu_idx; \
ret_type r; \
\
- r = debugfs_use_file_start(dentry, &srcu_idx); \
- if (likely(!r)) \
- r = real_fops->name(args); \
- debugfs_use_file_finish(srcu_idx); \
+ r = debugfs_file_get(dentry); \
+ if (unlikely(r)) \
+ return r; \
+ r = real_fops->name(args); \
+ debugfs_file_put(dentry); \
return r; \
}
@@ -172,18 +181,15 @@ FULL_PROXY_FUNC(unlocked_ioctl, long, fi
static unsigned int full_proxy_poll(struct file *filp,
struct poll_table_struct *wait)
{
- const struct dentry *dentry = F_DENTRY(filp);
const struct file_operations *real_fops = debugfs_real_fops(filp);
- int srcu_idx;
+ struct dentry *dentry = F_DENTRY(filp);
unsigned int r = 0;
- if (debugfs_use_file_start(dentry, &srcu_idx)) {
- debugfs_use_file_finish(srcu_idx);
+ if (debugfs_file_get(dentry))
return POLLHUP;
- }
r = real_fops->poll(filp, wait);
- debugfs_use_file_finish(srcu_idx);
+ debugfs_file_put(dentry);
return r;
}
@@ -227,16 +233,13 @@ static void __full_proxy_fops_init(struc
static int full_proxy_open(struct inode *inode, struct file *filp)
{
- const struct dentry *dentry = F_DENTRY(filp);
+ struct dentry *dentry = F_DENTRY(filp);
const struct file_operations *real_fops = NULL;
struct file_operations *proxy_fops = NULL;
- int srcu_idx, r;
+ int r = 0;
- r = debugfs_use_file_start(dentry, &srcu_idx);
- if (r) {
- r = -ENOENT;
- goto out;
- }
+ if (debugfs_file_get(dentry))
+ return -ENOENT;
real_fops = debugfs_real_fops(filp);
real_fops = fops_get(real_fops);
@@ -274,7 +277,7 @@ free_proxy:
kfree(proxy_fops);
fops_put(real_fops);
out:
- debugfs_use_file_finish(srcu_idx);
+ debugfs_file_put(dentry);
return r;
}
@@ -285,13 +288,14 @@ const struct file_operations debugfs_ful
ssize_t debugfs_attr_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos)
{
+ struct dentry *dentry = F_DENTRY(file);
ssize_t ret;
- int srcu_idx;
- ret = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
- if (likely(!ret))
- ret = simple_attr_read(file, buf, len, ppos);
- debugfs_use_file_finish(srcu_idx);
+ ret = debugfs_file_get(dentry);
+ if (unlikely(ret))
+ return ret;
+ ret = simple_attr_read(file, buf, len, ppos);
+ debugfs_file_put(dentry);
return ret;
}
EXPORT_SYMBOL_GPL(debugfs_attr_read);
@@ -299,13 +303,14 @@ EXPORT_SYMBOL_GPL(debugfs_attr_read);
ssize_t debugfs_attr_write(struct file *file, const char __user *buf,
size_t len, loff_t *ppos)
{
+ struct dentry *dentry = F_DENTRY(file);
ssize_t ret;
- int srcu_idx;
- ret = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
- if (likely(!ret))
- ret = simple_attr_write(file, buf, len, ppos);
- debugfs_use_file_finish(srcu_idx);
+ ret = debugfs_file_get(dentry);
+ if (unlikely(ret))
+ return ret;
+ ret = simple_attr_write(file, buf, len, ppos);
+ debugfs_file_put(dentry);
return ret;
}
EXPORT_SYMBOL_GPL(debugfs_attr_write);
@@ -739,14 +744,14 @@ ssize_t debugfs_read_file_bool(struct fi
{
char buf[3];
bool val;
- int r, srcu_idx;
+ int r;
+ struct dentry *dentry = F_DENTRY(file);
- r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
- if (likely(!r))
- val = *(bool *)file->private_data;
- debugfs_use_file_finish(srcu_idx);
- if (r)
+ r = debugfs_file_get(dentry);
+ if (unlikely(r))
return r;
+ val = *(bool *)file->private_data;
+ debugfs_file_put(dentry);
if (val)
buf[0] = 'Y';
@@ -764,8 +769,9 @@ ssize_t debugfs_write_file_bool(struct f
char buf[32];
size_t buf_size;
bool bv;
- int r, srcu_idx;
+ int r;
bool *val = file->private_data;
+ struct dentry *dentry = F_DENTRY(file);
buf_size = min(count, (sizeof(buf)-1));
if (copy_from_user(buf, user_buf, buf_size))
@@ -773,12 +779,11 @@ ssize_t debugfs_write_file_bool(struct f
buf[buf_size] = '\0';
if (strtobool(buf, &bv) == 0) {
- r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
- if (likely(!r))
- *val = bv;
- debugfs_use_file_finish(srcu_idx);
- if (r)
+ r = debugfs_file_get(dentry);
+ if (unlikely(r))
return r;
+ *val = bv;
+ debugfs_file_put(dentry);
}
return count;
@@ -840,14 +845,15 @@ static ssize_t read_file_blob(struct fil
size_t count, loff_t *ppos)
{
struct debugfs_blob_wrapper *blob = file->private_data;
+ struct dentry *dentry = F_DENTRY(file);
ssize_t r;
- int srcu_idx;
- r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx);
- if (likely(!r))
- r = simple_read_from_buffer(user_buf, count, ppos, blob->data,
- blob->size);
- debugfs_use_file_finish(srcu_idx);
+ r = debugfs_file_get(dentry);
+ if (unlikely(r))
+ return r;
+ r = simple_read_from_buffer(user_buf, count, ppos, blob->data,
+ blob->size);
+ debugfs_file_put(dentry);
return r;
}
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