From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- fs/fuse/dev.h | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 110 insertions(+) create mode 100644 fs/fuse/dev.h (limited to 'fs/fuse/dev.h') diff --git a/fs/fuse/dev.h b/fs/fuse/dev.h new file mode 100644 index 000000000..aed69fd14 --- /dev/null +++ b/fs/fuse/dev.h @@ -0,0 +1,110 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _FS_FUSE_DEV_H +#define _FS_FUSE_DEV_H + +#include + +/** Maximum number of outstanding background requests */ +#define FUSE_DEFAULT_MAX_BACKGROUND 12 + +struct fuse_conn; +struct fuse_chan; +struct fuse_dev; +struct fuse_args; +struct fuse_copy_state; +struct fuse_backing_map; +struct file; +struct folio; +enum fuse_notify_code; + +struct fuse_chan_param { + unsigned int minor; + unsigned int max_write; + unsigned int max_pages; +}; + +struct fuse_chan *fuse_chan_new(void); +struct fuse_chan *fuse_dev_chan_new(void); +void fuse_chan_release(struct fuse_chan *fch); +void fuse_chan_free(struct fuse_chan *fch); +unsigned int fuse_chan_num_background(struct fuse_chan *fch); +unsigned int fuse_chan_max_background(struct fuse_chan *fch); +void fuse_chan_max_background_set(struct fuse_chan *fch, unsigned int val); +unsigned int fuse_chan_num_waiting(struct fuse_chan *fch); +void fuse_chan_set_fc(struct fuse_chan *fch, struct fuse_conn *fc); +void fuse_chan_set_initialized(struct fuse_chan *fch, struct fuse_chan_param *param); +void fuse_chan_io_uring_enable(struct fuse_chan *fch); +ssize_t fuse_chan_send(struct fuse_chan *fch, struct fuse_args *args); +int fuse_chan_send_bg(struct fuse_chan *fch, struct fuse_args *args, gfp_t gfp_flags); +int fuse_chan_send_notify_reply(struct fuse_chan *fch, struct fuse_args *args, u64 unique); +void fuse_chan_resend(struct fuse_chan *fch); + +struct fuse_forget_link *fuse_alloc_forget(void); +void fuse_chan_queue_forget(struct fuse_chan *fch, struct fuse_forget_link *forget, + u64 nodeid, u64 nlookup); + +DEFINE_FREE(fuse_chan_free, struct fuse_chan *, if (_T) fuse_chan_free(_T)) + +/** + * Initialize the client device + */ +int fuse_dev_init(void); + +/** + * Cleanup the client device + */ +void fuse_dev_cleanup(void); + +void fuse_dev_install(struct fuse_dev *fud, struct fuse_chan *fch); +bool fuse_dev_verify(struct fuse_dev *fud, struct fuse_chan *fch); +void fuse_dev_put(struct fuse_dev *fud); +bool fuse_dev_is_installed(struct fuse_dev *fud); +bool fuse_dev_is_sync_init(struct fuse_dev *fud); +struct fuse_dev *fuse_dev_grab(struct file *file); + +void fuse_init_server_timeout(struct fuse_chan *fch, unsigned int timeout); + +/* Abort all requests */ +void fuse_chan_abort(struct fuse_chan *fch, bool abort_with_err); +void fuse_chan_wait_aborted(struct fuse_chan *fch); + +/** + * Acquire reference to fuse_conn + */ +struct fuse_conn *fuse_conn_get(struct fuse_conn *fc); + +/** + * Release reference to fuse_conn + */ +void fuse_conn_put(struct fuse_conn *fc); + +dev_t fuse_conn_get_id(struct fuse_conn *fc); + +void fuse_end_polls(struct fuse_conn *fc); +int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code, + unsigned int size, struct fuse_copy_state *cs); + +int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map); +int fuse_backing_close(struct fuse_conn *fc, int backing_id); + +int fuse_copy_one(struct fuse_copy_state *cs, void *val, unsigned size); +int fuse_copy_folio(struct fuse_copy_state *cs, struct folio **foliop, + unsigned offset, unsigned count, int zeroing); +void fuse_copy_finish(struct fuse_copy_state *cs); + +#ifdef CONFIG_FUSE_IO_URING +bool fuse_uring_enabled(void); +void fuse_uring_destruct(struct fuse_chan *fch); +#else /* CONFIG_FUSE_IO_URING */ +static inline bool fuse_uring_enabled(void) +{ + return false; +} + +static inline void fuse_uring_destruct(struct fuse_chan *fch) +{ +} +#endif /* CONFIG_FUSE_IO_URING */ + +#endif /* _FS_FUSE_DEV_H */ -- cgit v1.3.1