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Fixes for refcounting "struct linux_file" in the LinuxKPI.

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- Allow "struct linux_file" to be refcounted when its "_file" member
  is NULL by using its "f_count" field. The reference counts are
  transferred to the file structure when the file descriptor is
  installed.

- Add missing vdrop() calls for error cases during open().

- Set the "_file" member of "struct linux_file" during open. This
allows use of refcounting through get_file() and fput() with LinuxKPI
character devices.

MFC after:		1 week
Sponsored by:		Mellanox Technologies
This commit is contained in:
hselasky 2017-05-31 12:02:59 +00:00
parent b7e7cccc2e
commit f87686da6d
3 changed files with 49 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
sys/compat/linuxkpi/common/include/linux/file.h
View File

@ -2,7 +2,7 @@
* Copyright (c) 2010 Isilon Systems, Inc.
* Copyright (c) 2010 iX Systems, Inc.
* Copyright (c) 2010 Panasas, Inc.
* Copyright (c) 2013-2015 Mellanox Technologies, Ltd.
* Copyright (c) 2013-2017 Mellanox Technologies, Ltd.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -60,19 +60,24 @@ linux_fget(unsigned int fd)
return (struct linux_file *)file->f_data;
}
extern void linux_file_free(struct linux_file *filp);
static inline void
fput(struct linux_file *filp)
{
if (filp->_file == NULL) {
kfree(filp);
return;
}
if (refcount_release(&filp->_file->f_count)) {
_fdrop(filp->_file, curthread);
kfree(filp);
if (refcount_release(filp->_file == NULL ?
&filp->f_count : &filp->_file->f_count)) {
linux_file_free(filp);
}
}
static inline unsigned int
file_count(struct linux_file *filp)
{
return (filp->_file == NULL ?
filp->f_count : filp->_file->f_count);
}
static inline void
put_unused_fd(unsigned int fd)
{
@ -106,6 +111,10 @@ fd_install(unsigned int fd, struct linux_file *filp)
} else {
filp->_file = file;
finit(file, filp->f_mode, DTYPE_DEV, filp, &linuxfileops);
/* transfer reference count from "filp" to "file" */
while (refcount_release(&filp->f_count) == 0)
refcount_acquire(&file->f_count);
}
/* drop the extra reference */
@ -150,6 +159,8 @@ alloc_file(int mode, const struct file_operations *fops)
filp = kzalloc(sizeof(*filp), GFP_KERNEL);
if (filp == NULL)
return (NULL);
filp->f_count = 1;
filp->f_op = fops;
filp->f_mode = mode;
@ -171,7 +182,7 @@ static inline struct fd fdget(unsigned int fd)
return (struct fd){f};
}
#define file linux_file
#define fget linux_fget
#define file linux_file
#define fget(...) linux_fget(__VA_ARGS__)
#endif /* _LINUX_FILE_H_ */

9
sys/compat/linuxkpi/common/include/linux/fs.h
View File

@ -79,6 +79,7 @@ struct linux_file {
struct selinfo f_selinfo;
struct sigio *f_sigio;
struct vnode *f_vnode;
volatile u_int f_count;
};
#define file linux_file
@ -220,6 +221,14 @@ iminor(struct inode *inode)
return (minor(dev2unit(inode->v_rdev)));
}
static inline struct linux_file *
get_file(struct linux_file *f)
{
refcount_acquire(f->_file == NULL ? &f->f_count : &f->_file->f_count);
return (f);
}
static inline struct inode *
igrab(struct inode *inode)
{

21
sys/compat/linuxkpi/common/src/linux_compat.c
View File

@ -401,6 +401,20 @@ linux_file_dtor(void *cdp)
kfree(filp);
}
void
linux_file_free(struct linux_file *filp)
{
if (filp->_file == NULL) {
kfree(filp);
} else {
/*
* The close method of the character device or file
* will free the linux_file structure:
*/
_fdrop(filp->_file, curthread);
}
}
static int
linux_cdev_pager_populate(vm_object_t vm_obj, vm_pindex_t pidx, int fault_type,
vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
@ -593,9 +607,12 @@ linux_dev_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
vhold(file->f_vnode);
filp->f_vnode = file->f_vnode;
linux_set_current(td);
filp->_file = file;
if (filp->f_op->open) {
error = -filp->f_op->open(file->f_vnode, filp);
if (error) {
vdrop(filp->f_vnode);
kfree(filp);
goto done;
}
@ -603,6 +620,7 @@ linux_dev_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
error = devfs_set_cdevpriv(filp, linux_file_dtor);
if (error) {
filp->f_op->release(file->f_vnode, filp);
vdrop(filp->f_vnode);
kfree(filp);
}
done:
@ -622,8 +640,7 @@ linux_dev_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
if ((error = devfs_get_cdevpriv((void **)&filp)) != 0)
return (error);
filp->f_flags = file->f_flag;
devfs_clear_cdevpriv();
devfs_clear_cdevpriv();
return (0);
}