procfs_read/write(): rewrite synchronization for scalability and correctness
This commit is contained in:
Balazs Gerofi
@ -59,7 +59,6 @@ static const struct procfs_entry base_entry_stuff[];
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static const struct file_operations mckernel_forward_ro;
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static const struct file_operations mckernel_forward;
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static DECLARE_WAIT_QUEUE_HEAD(procfsq);
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static ssize_t mckernel_procfs_read(struct file *file, char __user *buf,
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size_t nbytes, loff_t *ppos);
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@ -106,14 +105,28 @@ getpath(struct procfs_list_entry *e, char *buf, int bufsize)
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/**
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* \brief Process SCD_MSG_PROCFS_ANSWER message.
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*
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* \param arg sent argument
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* \param err error info (redundant)
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* \param ud mcctrl_usrdata pointer
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* \param pid PID of the requesting process
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*/
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void
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procfs_answer(unsigned int arg, int err)
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void procfs_answer(struct mcctrl_usrdata *ud, int pid)
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{
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dprintk("procfs: received SCD_MSG_PROCFS_ANSWER message(err = %d).\n", err);
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wake_up_interruptible(&procfsq);
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struct mcctrl_per_proc_data *ppd = NULL;
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if (pid > 0) {
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ppd = mcctrl_get_per_proc_data(ud, pid);
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if (unlikely(!ppd)) {
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kprintf("%s: ERROR: no per-process structure for PID %d\n",
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__FUNCTION__, pid);
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return;
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}
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}
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wake_up_all(pid > 0 ? &ppd->wq_procfs : &ud->wq_procfs);
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if (pid > 0) {
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mcctrl_put_per_proc_data(ppd);
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}
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}
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static struct procfs_list_entry *
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@ -495,36 +508,84 @@ procfs_exit(int osnum)
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* This function conforms to the 2) way of fs/proc/generic.c
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* from linux-2.6.39.4.
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*/
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static ssize_t
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mckernel_procfs_read(struct file *file, char __user *buf, size_t nbytes,
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loff_t *ppos)
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static ssize_t __mckernel_procfs_read_write(
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struct file *file,
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char __user *buf, size_t nbytes,
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loff_t *ppos, int read_write)
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{
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struct inode * inode = file->f_inode;
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char *kern_buffer = NULL;
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int order = 0;
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volatile struct procfs_read *r = NULL;
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struct ikc_scd_packet isp;
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int ret;
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int ret, osnum, pid, retw;
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unsigned long pbuf;
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unsigned long count = nbytes;
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#if LINUX_VERSION_CODE < KERNEL_VERSION(3,10,0)
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struct proc_dir_entry *dp = PDE(inode);
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struct procfs_list_entry *e = dp->data;
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#else
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#else
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struct procfs_list_entry *e = PDE_DATA(inode);
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#endif
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#endif
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loff_t offset = *ppos;
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char pathbuf[PROCFS_NAME_MAX];
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char *path;
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char *path, *p;
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ihk_os_t os = NULL;
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struct mcctrl_usrdata *udp = NULL;
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struct mcctrl_per_proc_data *ppd = NULL;
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path = getpath(e, pathbuf, 256);
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dprintk("mckernel_procfs_read: invoked for %s, offset: %lu, count: %d\n",
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path, offset, count);
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if (count <= 0 || offset < 0) {
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return 0;
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}
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path = getpath(e, pathbuf, PROCFS_NAME_MAX);
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dprintk("%s: invoked for %s, offset: %lu, count: %lu\n",
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__FUNCTION__, path,
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(unsigned long)offset, count);
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/* Verify OS number */
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ret = sscanf(path, "mcos%d/", &osnum);
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if (ret != 1) {
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printk("%s: error: couldn't determine OS number\n", __FUNCTION__);
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return -EINVAL;
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}
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if (osnum != e->osnum) {
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printk("%s: error: OS numbers don't match\n", __FUNCTION__);
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return -EINVAL;
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}
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/* Is this request for a specific process? */
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p = strchr(path, '/') + 1;
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ret = sscanf(p, "%d/", &pid);
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if (ret != 1) {
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pid = -1;
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}
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os = osnum_to_os(osnum);
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if (!os) {
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printk("%s: error: no IHK OS data found for OS %d\n",
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__FUNCTION__, osnum);
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return -EINVAL;
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}
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udp = ihk_host_os_get_usrdata(os);
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if (!udp) {
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printk("%s: error: no MCCTRL data found for OS %d\n",
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__FUNCTION__, osnum);
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return -EINVAL;
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}
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if (pid > 0) {
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ppd = mcctrl_get_per_proc_data(udp, pid);
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if (unlikely(!ppd)) {
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printk("%s: error: no per-process structure for PID %d",
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__FUNCTION__, pid);
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return -EINVAL;
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}
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}
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while ((1 << order) < count) ++order;
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if (order > 12) {
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order -= 12;
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@ -536,10 +597,11 @@ mckernel_procfs_read(struct file *file, char __user *buf, size_t nbytes,
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/* NOTE: we need physically contigous memory to pass through IKC */
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kern_buffer = (char *)__get_free_pages(GFP_KERNEL, order);
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if (!kern_buffer) {
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printk("mckernel_procfs_read(): ERROR: allocating kernel buffer\n");
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return -ENOMEM;
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printk("%s: ERROR: allocating kernel buffer\n", __FUNCTION__);
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ret = -ENOMEM;
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goto out;
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}
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pbuf = virt_to_phys(kern_buffer);
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r = kmalloc(sizeof(struct procfs_read), GFP_KERNEL);
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@ -553,152 +615,96 @@ mckernel_procfs_read(struct file *file, char __user *buf, size_t nbytes,
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r->status = 0;
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r->offset = offset;
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r->count = count;
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r->readwrite = 0;
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r->readwrite = read_write;
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strncpy((char *)r->fname, path, PROCFS_NAME_MAX);
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isp.msg = SCD_MSG_PROCFS_REQUEST;
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isp.ref = 0;
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isp.arg = virt_to_phys(r);
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ret = mcctrl_ikc_send(osnum_to_os(e->osnum), 0, &isp);
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isp.pid = pid;
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ret = mcctrl_ikc_send(osnum_to_os(e->osnum),
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(pid > 0) ? ppd->ikc_target_cpu : 0, &isp);
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if (ret < 0) {
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goto out; /* error */
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}
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/* Wait for a reply. */
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ret = -EIO; /* default exit code */
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dprintk("now wait for a relpy\n");
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/* Wait for the status field of the procfs_read structure set ready. */
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if (wait_event_interruptible_timeout(procfsq, r->status != 0, HZ) == 0) {
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kprintf("ERROR: mckernel_procfs_read: timeout (1 sec).\n");
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dprintk("%s: waiting for reply\n", __FUNCTION__);
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retry_wait:
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/* Wait for the status field of the procfs_read structure,
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* wait on per-process or OS specific data depending on
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* who the request is for.
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*/
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if (pid > 0) {
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retw = wait_event_interruptible_timeout(ppd->wq_procfs,
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r->status != 0, HZ);
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}
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else {
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retw = wait_event_interruptible_timeout(udp->wq_procfs,
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r->status != 0, HZ);
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}
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/* Timeout? */
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if (retw == 0 && r->status == 0) {
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printk("%s: error: timeout (1 sec)\n", __FUNCTION__);
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goto out;
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}
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/* Wake up and check the result. */
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dprintk("mckernel_procfs_read: woke up. ret: %d, eof: %d\n", r->ret, r->eof);
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if (r->ret > 0) {
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if (copy_to_user(buf, kern_buffer, r->ret)) {
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kprintf("ERROR: mckernel_procfs_read: copy_to_user failed.\n");
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ret = -EFAULT;
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goto out;
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}
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/* Interrupted? */
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else if (retw == -ERESTARTSYS) {
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ret = -ERESTART;
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goto out;
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}
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/* Were we woken up by a reply to another procfs request? */
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else if (r->status == 0) {
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/* TODO: r->status is not set atomically, we could be woken
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* up with status == 0 and it could change to 1 while in this
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* code, we could potentially miss the wake_up()...
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*/
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printk("%s: stale wake-up, retrying\n", __FUNCTION__);
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goto retry_wait;
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}
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/* Wake up and check the result. */
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dprintk("%s: woke up. ret: %d, eof: %d\n",
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__FUNCTION__, r->ret, r->eof);
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if (r->ret > 0) {
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if (read_write == 0) {
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if (copy_to_user(buf, kern_buffer, r->ret)) {
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printk("%s: ERROR: copy_to_user failed.\n", __FUNCTION__);
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ret = -EFAULT;
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goto out;
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}
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}
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*ppos += r->ret;
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}
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ret = r->ret;
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out:
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if(kern_buffer)
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if (ppd)
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mcctrl_put_per_proc_data(ppd);
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if (kern_buffer)
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free_pages((uintptr_t)kern_buffer, order);
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if(r)
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if (r)
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kfree((void *)r);
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return ret;
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}
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static ssize_t
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mckernel_procfs_write(struct file *file, const char __user *buf, size_t nbytes,
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loff_t *ppos)
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static ssize_t mckernel_procfs_read(struct file *file,
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char __user *buf, size_t nbytes, loff_t *ppos)
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{
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struct inode * inode = file->f_inode;
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char *kern_buffer = NULL;
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int order = 0;
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volatile struct procfs_read *r = NULL;
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struct ikc_scd_packet isp;
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int ret;
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unsigned long pbuf;
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unsigned long count = nbytes;
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#if LINUX_VERSION_CODE < KERNEL_VERSION(3,10,0)
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struct proc_dir_entry *dp = PDE(inode);
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struct procfs_list_entry *e = dp->data;
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#else
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struct procfs_list_entry *e = PDE_DATA(inode);
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#endif
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loff_t offset = *ppos;
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char pathbuf[PROCFS_NAME_MAX];
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char *path;
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return __mckernel_procfs_read_write(file, buf, nbytes, ppos, 0);
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}
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path = getpath(e, pathbuf, 256);
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dprintk("mckernel_procfs_read: invoked for %s, offset: %lu, count: %d\n",
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path, offset, count);
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if (count <= 0 || offset < 0) {
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return 0;
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}
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while ((1 << order) < count) ++order;
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if (order > 12) {
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order -= 12;
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}
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else {
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order = 1;
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}
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/* NOTE: we need physically contigous memory to pass through IKC */
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kern_buffer = (char *)__get_free_pages(GFP_KERNEL, order);
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if (!kern_buffer) {
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printk("mckernel_procfs_read(): ERROR: allocating kernel buffer\n");
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return -ENOMEM;
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}
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if (copy_from_user(kern_buffer, buf, nbytes)) {
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ret = -EFAULT;
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goto out;
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}
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pbuf = virt_to_phys(kern_buffer);
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r = kmalloc(sizeof(struct procfs_read), GFP_KERNEL);
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if (r == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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dprintk("offset: %lx, count: %d, cpu: %d\n", offset, count, e->cpu);
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r->pbuf = pbuf;
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r->eof = 0;
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r->ret = -EIO; /* default */
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r->status = 0;
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r->offset = offset;
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r->count = count;
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r->readwrite = 1;
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strncpy((char *)r->fname, path, PROCFS_NAME_MAX);
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isp.msg = SCD_MSG_PROCFS_REQUEST;
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isp.ref = 0;
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isp.arg = virt_to_phys(r);
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ret = mcctrl_ikc_send(osnum_to_os(e->osnum), 0, &isp);
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if (ret < 0) {
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goto out; /* error */
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}
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/* Wait for a reply. */
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ret = -EIO; /* default exit code */
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dprintk("now wait for a relpy\n");
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/* Wait for the status field of the procfs_read structure set ready. */
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if (wait_event_interruptible_timeout(procfsq, r->status != 0, HZ) == 0) {
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kprintf("ERROR: mckernel_procfs_read: timeout (1 sec).\n");
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goto out;
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}
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/* Wake up and check the result. */
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dprintk("mckernel_procfs_read: woke up. ret: %d, eof: %d\n", r->ret, r->eof);
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if (r->ret > 0) {
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*ppos += r->ret;
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}
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ret = r->ret;
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out:
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if(kern_buffer)
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free_pages((uintptr_t)kern_buffer, order);
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if(r)
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kfree((void *)r);
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return ret;
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static ssize_t mckernel_procfs_write(struct file *file,
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const char __user *buf, size_t nbytes, loff_t *ppos)
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{
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return __mckernel_procfs_read_write(file,
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(char __user *)buf, nbytes, ppos, 1);
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}
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static loff_t
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