Adds a new type of supported control file representation, a map from strings to u64 values. Signed-off-by: Paul Menage --- include/linux/cgroup.h | 19 +++++++++++++++ kernel/cgroup.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 79 insertions(+), 1 deletion(-) Index: cgroupmap-2.6.24-mm1/include/linux/cgroup.h =================================================================== --- cgroupmap-2.6.24-mm1.orig/include/linux/cgroup.h +++ cgroupmap-2.6.24-mm1/include/linux/cgroup.h @@ -191,6 +191,17 @@ enum cgroup_file_type { CGROUP_FILE_VOID, CGROUP_FILE_U64, CGROUP_FILE_STRING, + CGROUP_FILE_MAP, +}; + +/* + * cgroup_map_cb is an abstract callback API for reporting map-valued + * control files + */ + +struct cgroup_map_cb { + int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value); + void *state; }; #define MAX_CFTYPE_NAME 64 @@ -215,6 +226,14 @@ struct cftype { * single integer. Use it in place of read() */ u64 (*read_uint) (struct cgroup *cont, struct cftype *cft); + /* + * read_map() is used for defining a map of key/value + * pairs. It should call cb->fill(cb, key, value) for each + * entry. + */ + int (*read_map) (struct cgroup *cont, struct cftype *cft, + struct cgroup_map_cb *cb); + ssize_t (*write) (struct cgroup *cont, struct cftype *cft, struct file *file, const char __user *buf, size_t nbytes, loff_t *ppos); Index: cgroupmap-2.6.24-mm1/kernel/cgroup.c =================================================================== --- cgroupmap-2.6.24-mm1.orig/kernel/cgroup.c +++ cgroupmap-2.6.24-mm1/kernel/cgroup.c @@ -1488,6 +1488,46 @@ static ssize_t cgroup_file_read(struct f return -EINVAL; } +/* + * seqfile ops/methods for returning structured data. Currently just + * supports string->u64 maps, but can be extended in future. + */ + +struct cgroup_seqfile_state { + struct cftype *cft; + struct cgroup *cgroup; +}; + +static int cgroup_map_add(struct cgroup_map_cb *cb, const char *key, u64 value) +{ + struct seq_file *sf = cb->state; + return seq_printf(sf, "%s: %llu\n", key, value); +} + +static int cgroup_seqfile_show(struct seq_file *m, void *arg) +{ + struct cgroup_seqfile_state *state = m->private; + struct cftype *cft = state->cft; + struct cgroup_map_cb cb = { + .fill = cgroup_map_add, + .state = m, + }; + if (cft->read_map) { + return cft->read_map(state->cgroup, cft, &cb); + } else { + BUG(); + } +} + +int cgroup_seqfile_release(struct inode *inode, struct file *file) +{ + struct seq_file *seq = file->private_data; + kfree(seq->private); + return single_release(inode, file); +} + +static struct file_operations cgroup_seqfile_operations; + static int cgroup_file_open(struct inode *inode, struct file *file) { int err; @@ -1500,7 +1540,18 @@ static int cgroup_file_open(struct inode cft = __d_cft(file->f_dentry); if (!cft) return -ENODEV; - if (cft->open) + if (cft->read_map) { + struct cgroup_seqfile_state *state = + kzalloc(sizeof(*state), GFP_USER); + if (!state) + return -ENOMEM; + state->cft = cft; + state->cgroup = __d_cgrp(file->f_dentry->d_parent); + file->f_op = &cgroup_seqfile_operations; + err = single_open(file, cgroup_seqfile_show, state); + if (err < 0) + kfree(state); + } else if (cft->open) err = cft->open(inode, file); else err = 0; @@ -1539,6 +1590,12 @@ static struct file_operations cgroup_fil .release = cgroup_file_release, }; +static struct file_operations cgroup_seqfile_operations = { + .read = seq_read, + .llseek = seq_lseek, + .release = cgroup_seqfile_release, +}; + static struct inode_operations cgroup_dir_inode_operations = { .lookup = simple_lookup, .mkdir = cgroup_mkdir, @@ -2206,6 +2263,8 @@ static int cgroup_api_show(struct seq_fi if (type == CGROUP_FILE_UNKNOWN) { if (cft->read_uint) type = CGROUP_FILE_U64; + else if (cft->read_map) + type = CGROUP_FILE_MAP; else if (cft->read) type = CGROUP_FILE_STRING; else if (!cft->open) -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/