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SubjectRe: [RFC v10][PATCH 08/13] Dump open file descriptors
On Wed, Nov 26, 2008 at 08:04:39PM -0500, Oren Laadan wrote:
> +int cr_scan_fds(struct files_struct *files, int **fdtable)
> +{
> + struct fdtable *fdt;
> + int *fds;
> + int i, n = 0;
> + int tot = CR_DEFAULT_FDTABLE;
> +
> + fds = kmalloc(tot * sizeof(*fds), GFP_KERNEL);
> + if (!fds)
> + return -ENOMEM;
> +
> + /*
> + * We assume that the target task is frozen (or that we checkpoint
> + * ourselves), so we can safely proceed after krealloc() from where
> + * we left off; in the worst cases restart will fail.
> + */

Task may be frozen, but it may share the table with any number of other
tasks...

> + spin_lock(&files->file_lock);
> + rcu_read_lock();
> + fdt = files_fdtable(files);
> + for (i = 0; i < fdt->max_fds; i++) {
> + if (!fcheck_files(files, i))
> + continue;
> + if (n == tot) {
> + /*
> + * fcheck_files() is safe with drop/re-acquire
> + * of the lock, because it tests: fd < max_fds
> + */
> + spin_unlock(&files->file_lock);
> + rcu_read_unlock();
> + tot *= 2; /* won't overflow: kmalloc will fail */
> + fds = krealloc(fds, tot * sizeof(*fds), GFP_KERNEL);
> + if (!fds)
> + return -ENOMEM;
> + rcu_read_lock();
> + spin_lock(&files->file_lock);
> + }
> + fds[n++] = i;
> + }
> + rcu_read_unlock();
> + spin_unlock(&files->file_lock);
> +
> + *fdtable = fds;
> + return n;
> +}

> + switch (inode->i_mode & S_IFMT) {
> + case S_IFREG:
> + fd_type = CR_FD_FILE;
> + break;
> + case S_IFDIR:
> + fd_type = CR_FD_DIR;
> + break;
> + case S_IFLNK:
> + fd_type = CR_FD_LINK;

Opened symlinks? May I have whatever you'd been smoking, please?


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