linux/fs/coda/psdev.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* An implementation of a loadable kernel mode driver providing
* multiple kernel/user space bidirectional communications links.
*
* Author: Alan Cox <alan@lxorguk.ukuu.org.uk>
*
* Adapted to become the Linux 2.0 Coda pseudo device
* Peter Braam <braam@maths.ox.ac.uk>
* Michael Callahan <mjc@emmy.smith.edu>
*
* Changes for Linux 2.1
* Copyright (c) 1997 Carnegie-Mellon University
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/time.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <linux/fcntl.h>
#include <linux/delay.h>
#include <linux/skbuff.h>
#include <linux/proc_fs.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/pid_namespace.h>
#include <asm/io.h>
#include <linux/uaccess.h>
#include <linux/coda.h>
#include "coda_psdev.h"
#include "coda_linux.h"
#include "coda_int.h"
/* statistics */
int coda_hard; /* allows signals during upcalls */
unsigned long coda_timeout = 30; /* .. secs, then signals will dequeue */
struct venus_comm coda_comms[MAX_CODADEVS];
static struct class *coda_psdev_class;
/*
* Device operations
*/
static __poll_t coda_psdev_poll(struct file *file, poll_table * wait)
{
struct venus_comm *vcp = (struct venus_comm *) file->private_data;
__poll_t mask = EPOLLOUT | EPOLLWRNORM;
poll_wait(file, &vcp->vc_waitq, wait);
mutex_lock(&vcp->vc_mutex);
if (!list_empty(&vcp->vc_pending))
mask |= EPOLLIN | EPOLLRDNORM;
mutex_unlock(&vcp->vc_mutex);
return mask;
}
static long coda_psdev_ioctl(struct file * filp, unsigned int cmd, unsigned long arg)
{
unsigned int data;
switch(cmd) {
case CIOC_KERNEL_VERSION:
data = CODA_KERNEL_VERSION;
return put_user(data, (int __user *) arg);
default:
return -ENOTTY;
}
return 0;
}
/*
* Receive a message written by Venus to the psdev
*/
static ssize_t coda_psdev_write(struct file *file, const char __user *buf,
size_t nbytes, loff_t *off)
{
struct venus_comm *vcp = (struct venus_comm *) file->private_data;
struct upc_req *req = NULL;
struct upc_req *tmp;
struct list_head *lh;
struct coda_in_hdr hdr;
ssize_t retval = 0, count = 0;
int error;
/* make sure there is enough to copy out the (opcode, unique) values */
if (nbytes < (2 * sizeof(u_int32_t)))
return -EINVAL;
/* Peek at the opcode, uniquefier */
if (copy_from_user(&hdr, buf, 2 * sizeof(u_int32_t)))
return -EFAULT;
if (DOWNCALL(hdr.opcode)) {
union outputArgs *dcbuf;
int size = sizeof(*dcbuf);
if ( nbytes < sizeof(struct coda_out_hdr) ) {
pr_warn("coda_downcall opc %d uniq %d, not enough!\n",
hdr.opcode, hdr.unique);
count = nbytes;
goto out;
}
if ( nbytes > size ) {
pr_warn("downcall opc %d, uniq %d, too much!",
hdr.opcode, hdr.unique);
nbytes = size;
}
dcbuf = kvmalloc(nbytes, GFP_KERNEL);
if (!dcbuf) {
retval = -ENOMEM;
goto out;
}
if (copy_from_user(dcbuf, buf, nbytes)) {
kvfree(dcbuf);
retval = -EFAULT;
goto out;
}
/* what downcall errors does Venus handle ? */
error = coda_downcall(vcp, hdr.opcode, dcbuf, nbytes);
kvfree(dcbuf);
if (error) {
pr_warn("%s: coda_downcall error: %d\n",
__func__, error);
retval = error;
goto out;
}
count = nbytes;
goto out;
}
/* Look for the message on the processing queue. */
mutex_lock(&vcp->vc_mutex);
list_for_each(lh, &vcp->vc_processing) {
tmp = list_entry(lh, struct upc_req , uc_chain);
if (tmp->uc_unique == hdr.unique) {
req = tmp;
list_del(&req->uc_chain);
break;
}
}
mutex_unlock(&vcp->vc_mutex);
if (!req) {
pr_warn("%s: msg (%d, %d) not found\n",
__func__, hdr.opcode, hdr.unique);
retval = -ESRCH;
goto out;
}
/* move data into response buffer. */
if (req->uc_outSize < nbytes) {
pr_warn("%s: too much cnt: %d, cnt: %ld, opc: %d, uniq: %d.\n",
__func__, req->uc_outSize, (long)nbytes,
hdr.opcode, hdr.unique);
nbytes = req->uc_outSize; /* don't have more space! */
}
if (copy_from_user(req->uc_data, buf, nbytes)) {
req->uc_flags |= CODA_REQ_ABORT;
wake_up(&req->uc_sleep);
retval = -EFAULT;
goto out;
}
/* adjust outsize. is this useful ?? */
req->uc_outSize = nbytes;
req->uc_flags |= CODA_REQ_WRITE;
count = nbytes;
/* Convert filedescriptor into a file handle */
if (req->uc_opcode == CODA_OPEN_BY_FD) {
struct coda_open_by_fd_out *outp =
(struct coda_open_by_fd_out *)req->uc_data;
if (!outp->oh.result) {
outp->fh = fget(outp->fd);
if (!outp->fh)
return -EBADF;
}
}
wake_up(&req->uc_sleep);
out:
return(count ? count : retval);
}
/*
* Read a message from the kernel to Venus
*/
static ssize_t coda_psdev_read(struct file * file, char __user * buf,
size_t nbytes, loff_t *off)
{
DECLARE_WAITQUEUE(wait, current);
struct venus_comm *vcp = (struct venus_comm *) file->private_data;
struct upc_req *req;
ssize_t retval = 0, count = 0;
if (nbytes == 0)
return 0;
mutex_lock(&vcp->vc_mutex);
add_wait_queue(&vcp->vc_waitq, &wait);
set_current_state(TASK_INTERRUPTIBLE);
while (list_empty(&vcp->vc_pending)) {
if (file->f_flags & O_NONBLOCK) {
retval = -EAGAIN;
break;
}
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
mutex_unlock(&vcp->vc_mutex);
schedule();
mutex_lock(&vcp->vc_mutex);
}
set_current_state(TASK_RUNNING);
remove_wait_queue(&vcp->vc_waitq, &wait);
if (retval)
goto out;
req = list_entry(vcp->vc_pending.next, struct upc_req,uc_chain);
list_del(&req->uc_chain);
/* Move the input args into userspace */
count = req->uc_inSize;
if (nbytes < req->uc_inSize) {
pr_warn("%s: Venus read %ld bytes of %d in message\n",
__func__, (long)nbytes, req->uc_inSize);
count = nbytes;
}
if (copy_to_user(buf, req->uc_data, count))
retval = -EFAULT;
/* If request was not a signal, enqueue and don't free */
if (!(req->uc_flags & CODA_REQ_ASYNC)) {
req->uc_flags |= CODA_REQ_READ;
list_add_tail(&(req->uc_chain), &vcp->vc_processing);
goto out;
}
kvfree(req->uc_data);
kfree(req);
out:
mutex_unlock(&vcp->vc_mutex);
return (count ? count : retval);
}
static int coda_psdev_open(struct inode * inode, struct file * file)
{
struct venus_comm *vcp;
int idx, err;
if (task_active_pid_ns(current) != &init_pid_ns)
return -EINVAL;
if (current_user_ns() != &init_user_ns)
return -EINVAL;
idx = iminor(inode);
if (idx < 0 || idx >= MAX_CODADEVS)
return -ENODEV;
err = -EBUSY;
vcp = &coda_comms[idx];
mutex_lock(&vcp->vc_mutex);
if (!vcp->vc_inuse) {
vcp->vc_inuse++;
INIT_LIST_HEAD(&vcp->vc_pending);
INIT_LIST_HEAD(&vcp->vc_processing);
init_waitqueue_head(&vcp->vc_waitq);
vcp->vc_sb = NULL;
vcp->vc_seq = 0;
file->private_data = vcp;
err = 0;
}
mutex_unlock(&vcp->vc_mutex);
return err;
}
static int coda_psdev_release(struct inode * inode, struct file * file)
{
struct venus_comm *vcp = (struct venus_comm *) file->private_data;
struct upc_req *req, *tmp;
if (!vcp || !vcp->vc_inuse ) {
pr_warn("%s: Not open.\n", __func__);
return -1;
}
mutex_lock(&vcp->vc_mutex);
/* Wakeup clients so they can return. */
list_for_each_entry_safe(req, tmp, &vcp->vc_pending, uc_chain) {
list_del(&req->uc_chain);
/* Async requests need to be freed here */
if (req->uc_flags & CODA_REQ_ASYNC) {
kvfree(req->uc_data);
kfree(req);
continue;
}
req->uc_flags |= CODA_REQ_ABORT;
wake_up(&req->uc_sleep);
}
list_for_each_entry_safe(req, tmp, &vcp->vc_processing, uc_chain) {
list_del(&req->uc_chain);
req->uc_flags |= CODA_REQ_ABORT;
wake_up(&req->uc_sleep);
}
file->private_data = NULL;
vcp->vc_inuse--;
mutex_unlock(&vcp->vc_mutex);
return 0;
}
static const struct file_operations coda_psdev_fops = {
.owner = THIS_MODULE,
.read = coda_psdev_read,
.write = coda_psdev_write,
.poll = coda_psdev_poll,
.unlocked_ioctl = coda_psdev_ioctl,
.open = coda_psdev_open,
.release = coda_psdev_release,
llseek: automatically add .llseek fop All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
2010-08-15 16:52:59 +00:00
.llseek = noop_llseek,
};
static int __init init_coda_psdev(void)
{
int i, err = 0;
if (register_chrdev(CODA_PSDEV_MAJOR, "coda", &coda_psdev_fops)) {
pr_err("%s: unable to get major %d\n",
__func__, CODA_PSDEV_MAJOR);
return -EIO;
}
coda_psdev_class = class_create(THIS_MODULE, "coda");
if (IS_ERR(coda_psdev_class)) {
err = PTR_ERR(coda_psdev_class);
goto out_chrdev;
}
for (i = 0; i < MAX_CODADEVS; i++) {
mutex_init(&(&coda_comms[i])->vc_mutex);
device_create(coda_psdev_class, NULL,
MKDEV(CODA_PSDEV_MAJOR, i), NULL, "cfs%d", i);
}
coda_sysctl_init();
goto out;
out_chrdev:
unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
out:
return err;
}
MODULE_AUTHOR("Jan Harkes, Peter J. Braam");
MODULE_DESCRIPTION("Coda Distributed File System VFS interface");
MODULE_ALIAS_CHARDEV_MAJOR(CODA_PSDEV_MAJOR);
MODULE_LICENSE("GPL");
MODULE_VERSION("7.0");
static int __init init_coda(void)
{
int status;
int i;
status = coda_init_inodecache();
if (status)
goto out2;
status = init_coda_psdev();
if ( status ) {
pr_warn("Problem (%d) in init_coda_psdev\n", status);
goto out1;
}
status = register_filesystem(&coda_fs_type);
if (status) {
pr_warn("failed to register filesystem!\n");
goto out;
}
return 0;
out:
for (i = 0; i < MAX_CODADEVS; i++)
device_destroy(coda_psdev_class, MKDEV(CODA_PSDEV_MAJOR, i));
class_destroy(coda_psdev_class);
unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
coda_sysctl_clean();
out1:
coda_destroy_inodecache();
out2:
return status;
}
static void __exit exit_coda(void)
{
int err, i;
err = unregister_filesystem(&coda_fs_type);
if (err != 0)
pr_warn("failed to unregister filesystem\n");
for (i = 0; i < MAX_CODADEVS; i++)
device_destroy(coda_psdev_class, MKDEV(CODA_PSDEV_MAJOR, i));
class_destroy(coda_psdev_class);
unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
coda_sysctl_clean();
coda_destroy_inodecache();
}
module_init(init_coda);
module_exit(exit_coda);