Serge E. Hallyn wrote: > Quoting Nadia.Derbey@xxxxxxxx (Nadia.Derbey@xxxxxxxx): > >>PATCH [06/06] >> >>This patch introduces the .write seq operation for /proc/pid/semundo. >> >>In order to simplify the locking strategy, the write operation is only allowed >>to 'current'. >> >> >>Signed-off-by: Nadia Derbey <Nadia.Derbey@xxxxxxxx> > > > Acked-by: Serge Hallyn <serue@xxxxxxxxxx> > > Have you written a patch to cryo in light of the new (target==current) > restriction? Nop, will do that. Regards, Nadia > > thanks, > -serge > > >>--- >> fs/proc/base.c | 2 >> ipc/sem.c | 250 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++- >> 2 files changed, 250 insertions(+), 2 deletions(-) >> >>Index: linux-2.6.26-rc5-mm3/fs/proc/base.c >>=================================================================== >>--- linux-2.6.26-rc5-mm3.orig/fs/proc/base.c 2008-06-24 10:03:33.000000000 +0200 >>+++ linux-2.6.26-rc5-mm3/fs/proc/base.c 2008-06-24 13:21:44.000000000 +0200 >>@@ -2526,7 +2526,7 @@ static const struct pid_entry tgid_base_ >> INF("io", S_IRUGO, tgid_io_accounting), >> #endif >> #ifdef CONFIG_SYSVIPC >>- REG("semundo", S_IRUGO, semundo), >>+ REG("semundo", S_IWUSR|S_IRUGO, semundo), >> #endif >> }; >> >>Index: linux-2.6.26-rc5-mm3/ipc/sem.c >>=================================================================== >>--- linux-2.6.26-rc5-mm3.orig/ipc/sem.c 2008-06-24 12:59:15.000000000 +0200 >>+++ linux-2.6.26-rc5-mm3/ipc/sem.c 2008-06-25 08:56:07.000000000 +0200 >>@@ -1554,7 +1554,27 @@ static int semundo_open(struct inode *in >> goto out_err; >> } >> >>- ulp = get_proc_ulp(task); >>+ if (file->f_flags & O_WRONLY || file->f_flags & O_RDWR) { >>+ /* >>+ * Writing is only allowed to current >>+ */ >>+ if (task != current) { >>+ put_task_struct(task); >>+ ret = -EPERM; >>+ goto out_err; >>+ } >>+ /* >>+ * No need to increment the undo_list's refcnt: only current >>+ * can be freeing it through exit, and we are current. >>+ * Only signal through the ulp NULL pointer that it won't be >>+ * necessary to decrement the refcnt during release. >>+ * Actually, in this path the undo_list will be gotten during >>+ * the write operation. >>+ */ >>+ ulp = NULL; >>+ } else >>+ ulp = get_proc_ulp(task); >>+ >> ns = get_ipc_ns(task->nsproxy->ipc_ns); >> put_task_struct(task); >> >>@@ -1574,6 +1594,233 @@ out_err: >> return ret; >> } >> >>+/* Skip all spaces at the beginning of the buffer */ >>+static inline int skip_space(const char __user **buf, size_t *len) >>+{ >>+ char c = 0; >>+ while (*len) { >>+ if (get_user(c, *buf)) >>+ return -EFAULT; >>+ if (c != '\t' && c != ' ') >>+ break; >>+ --*len; >>+ ++*buf; >>+ } >>+ return c; >>+} >>+ >>+/* Retrieve the first numerical value contained in the string. >>+ * Note: The value is supposed to be a 32-bit integer. >>+ */ >>+static inline int get_next_value(const char __user **buf, size_t *len, int *val) >>+{ >>+#define BUFLEN 11 >>+ int err, neg = 0, left; >>+ char s[BUFLEN], *p; >>+ >>+ err = skip_space(buf, len); >>+ if (err < 0) >>+ return err; >>+ if (!*len) >>+ return INT_MAX; >>+ if (err == '\n') { >>+ ++*buf; >>+ --*len; >>+ return INT_MAX; >>+ } >>+ if (err == '-') { >>+ ++*buf; >>+ --*len; >>+ neg = 1; >>+ } >>+ >>+ left = *len; >>+ if (left > sizeof(s) - 1) >>+ left = sizeof(s) - 1; >>+ if (copy_from_user(s, *buf, left)) >>+ return -EFAULT; >>+ >>+ s[left] = 0; >>+ p = s; >>+ if (*p < '0' || *p > '9') >>+ return -EINVAL; >>+ >>+ *val = simple_strtoul(p, &p, 0); >>+ if (neg) >>+ *val = -(*val); >>+ >>+ left = p-s; >>+ (*len) -= left; >>+ (*buf) += left; >>+ >>+ return 0; >>+#undef BUFLEN >>+} >>+ >>+/* >>+ * Reads a line from /proc/self/semundo. >>+ * Returns the number of undo values read (or errcode upon failure). >>+ * @id: pointer to the semid (filled in with 1st field in the line) >>+ * @array: semundo values (filled in iwth remaining fields in the line). >>+ * @array_len: max # of expected semundo values >>+ */ >>+static inline int semundo_readline(const char __user **buf, size_t *left, >>+ int *id, short *array, int array_len) >>+{ >>+ int i, val, err; >>+ >>+ /* Read semid */ >>+ err = get_next_value(buf, left, id); >>+ if (err) >>+ return err; >>+ >>+ /* Read all (semundo-) values of a full line */ >>+ for (i = 0; ; i++) { >>+ err = get_next_value(buf, left, &val); >>+ if (err < 0) >>+ return err; >>+ /* reached end of line or end of buffer */ >>+ if (err == INT_MAX) >>+ break; >>+ /* Return an error if we get more values than expected */ >>+ if (i < array_len) >>+ array[i] = val; >>+ else >>+ return -EINVAL; >>+ } >>+ return i; >>+} >>+ >>+/* >>+ * sets or updates the undo values for the undo_list of a given semaphore id. >>+ * This is exactly the same code sequence as sys_semtimedop if we have undos. >>+ */ >>+static inline int semundo_update(struct ipc_namespace *ns, int semid, >>+ short *array, int size) >>+{ >>+ struct sem_undo *un; >>+ struct sem_array *sma; >>+ int ret = 0; >>+ >>+ un = find_alloc_undo(ns, semid); >>+ if (IS_ERR(un)) { >>+ ret = PTR_ERR(un); >>+ goto out; >>+ } >>+ >>+ /* lookup the sem_array */ >>+ sma = sem_lock(ns, semid); >>+ if (IS_ERR(sma)) { >>+ ret = PTR_ERR(sma); >>+ rcu_read_unlock(); >>+ goto out; >>+ } >>+ >>+ /* >>+ * find_alloc_undo opened an rcu read section to protect un. >>+ * Releasing it here is safe: >>+ * . sem_lock is held, so we are protected against IPC_RMID >>+ * . the refcnt won't fall to 0 since exit_sem only operates on >>+ * current and we are the current. >>+ */ >>+ rcu_read_unlock(); >>+ >>+ /* >>+ * semid identifiers are not unique - find_alloc_undo() may have >>+ * allocated an undo structure, it was invalidated by an RMID and now >>+ * a new array received the same id. >>+ * Check and fail. >>+ * This case can be detected checking un->semid. The existance of >>+ * "un" itself is guaranteed by rcu. >>+ */ >>+ if (un->semid == -1) { >>+ ret = -EIDRM; >>+ goto out_unlock; >>+ } >>+ >>+ /* >>+ * If the number of values given does not match the number of >>+ * semaphores in the array, consider this as an error. >>+ */ >>+ if (size != sma->sem_nsems) { >>+ ret = -EINVAL; >>+ goto out_unlock; >>+ } >>+ >>+ /* update the undo values */ >>+ while (--size >= 0) >>+ un->semadj[size] = array[size]; >>+ >>+ /* maybe some queued-up processes were waiting for this */ >>+ update_queue(sma); >>+ >>+out_unlock: >>+ sem_unlock(sma); >>+out: >>+ return ret; >>+} >>+ >>+/* >>+ * write operation for /proc/self/semundo file >>+ * >>+ * Only current is allowed to write to its semundo file. >>+ * >>+ * The expected string format is: >>+ * "<semID> <val1> <val2> ... <valN>" >>+ * >>+ * It sets (or updates) the sem_undo list for 'current' and the target >>+ * <semID>, to the given 'undo' values. >>+ * >>+ * <semID> must match an existing semaphore array. >>+ * The number of values following <semID> must match the number of semaphores >>+ * in the corresponding array. >>+ * >>+ * Multiple semID's can be passed simultaneously: newline ('\n') is considered >>+ * as a separator in that case. >>+ * >>+ * Note: it is not allowed to set the sem_undo list for a given semID using >>+ * mutliple write calls. >>+ */ >>+static ssize_t semundo_write(struct file *file, const char __user *buf, >>+ size_t count, loff_t *ppos) >>+{ >>+ struct seq_file *m = file->private_data; >>+ short *array; >>+ int err, max_sem, semid = 0; >>+ size_t left = count; >>+ struct undo_list_data *data = m->private; >>+ struct ipc_namespace *ns = data->ipc_ns; >>+ >>+ if (data->undo_list) >>+ /* Should never happen */ >>+ return -EINVAL; >>+ >>+ max_sem = ns->sc_semmsl; >>+ >>+ array = kmalloc(sizeof(short)*max_sem, GFP_KERNEL); >>+ if (array == NULL) >>+ return -ENOMEM; >>+ >>+ while (left) { >>+ int nval; >>+ >>+ nval = semundo_readline(&buf, &left, &semid, array, max_sem); >>+ if (nval < 0) { >>+ err = nval; >>+ goto out; >>+ } >>+ >>+ err = semundo_update(ns, semid, array, nval); >>+ if (err) >>+ goto out; >>+ } >>+ err = count - left; >>+ >>+out: >>+ kfree(array); >>+ return err; >>+} >>+ >> static int semundo_release(struct inode *inode, struct file *file) >> { >> struct seq_file *m = file->private_data; >>@@ -1590,6 +1837,7 @@ static int semundo_release(struct inode >> const struct file_operations proc_semundo_operations = { >> .open = semundo_open, >> .read = seq_read, >>+ .write = semundo_write, >> .llseek = seq_lseek, >> .release = semundo_release, >> }; >> >>-- > > > _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers