Using the newly introduced tida for allocating pty indexes saves around 16KB of runtime memory. Since tida does it's own internal locking, we don't need to protect it with the &allocated_ptys_lock and do the whole "preallocate outside lock, loop if we're extremely unlucky", thus allowing us simplify devpts_new_index somewhat.
Signed-off-by: Rasmus Villemoes <[email protected]> --- fs/devpts/inode.c | 28 ++++++++++------------------ 1 file changed, 10 insertions(+), 18 deletions(-) diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 108df2e3602c..ea40437f246a 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -22,7 +22,7 @@ #include <linux/tty.h> #include <linux/mutex.h> #include <linux/magic.h> -#include <linux/idr.h> +#include <linux/tida.h> #include <linux/devpts_fs.h> #include <linux/parser.h> #include <linux/fsnotify.h> @@ -122,7 +122,7 @@ static const match_table_t tokens = { }; struct pts_fs_info { - struct ida allocated_ptys; + struct tida allocated_ptys; struct pts_mount_opts mount_opts; struct super_block *sb; struct dentry *ptmx_dentry; @@ -377,7 +377,7 @@ static void *new_pts_fs_info(struct super_block *sb) if (!fsi) return NULL; - ida_init(&fsi->allocated_ptys); + tida_init(&fsi->allocated_ptys); fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; fsi->sb = sb; @@ -453,7 +453,7 @@ static void devpts_kill_sb(struct super_block *sb) struct pts_fs_info *fsi = DEVPTS_SB(sb); if (fsi) - ida_destroy(&fsi->allocated_ptys); + tida_destroy(&fsi->allocated_ptys); kfree(fsi); kill_litter_super(sb); } @@ -473,29 +473,21 @@ static struct file_system_type devpts_fs_type = { int devpts_new_index(struct pts_fs_info *fsi) { int index; - int ida_ret; -retry: - if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) - return -ENOMEM; + index = tida_get(&fsi->allocated_ptys, GFP_KERNEL); + if (index < 0) + return index; mutex_lock(&allocated_ptys_lock); if (pty_count >= (pty_limit - (fsi->mount_opts.reserve ? 0 : pty_reserve))) { + tida_put(&fsi->allocated_ptys, index); mutex_unlock(&allocated_ptys_lock); return -ENOSPC; } - ida_ret = ida_get_new(&fsi->allocated_ptys, &index); - if (ida_ret < 0) { - mutex_unlock(&allocated_ptys_lock); - if (ida_ret == -EAGAIN) - goto retry; - return -EIO; - } - if (index >= fsi->mount_opts.max) { - ida_remove(&fsi->allocated_ptys, index); + tida_put(&fsi->allocated_ptys, index); mutex_unlock(&allocated_ptys_lock); return -ENOSPC; } @@ -507,7 +499,7 @@ int devpts_new_index(struct pts_fs_info *fsi) void devpts_kill_index(struct pts_fs_info *fsi, int idx) { mutex_lock(&allocated_ptys_lock); - ida_remove(&fsi->allocated_ptys, idx); + tida_put(&fsi->allocated_ptys, idx); pty_count--; mutex_unlock(&allocated_ptys_lock); } -- 2.1.4
