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| author | Kui-Feng Lee <thinker.li@gmail.com> | 2024-05-29 23:59:41 -0700 |
|---|---|---|
| committer | Martin KaFai Lau <martin.lau@kernel.org> | 2024-05-30 15:34:13 -0700 |
| commit | 1adddc97aa44c8783f9f0276ea70854d56f9f6df (patch) | |
| tree | 9bf857f946cbe8a3c1cdb08f759f981bb11d8f09 /kernel/bpf/bpf_struct_ops.c | |
| parent | 6fb2544ea1493f52e50b753604791c01bd2cf897 (diff) | |
| download | linux-1adddc97aa44c8783f9f0276ea70854d56f9f6df.tar.gz linux-1adddc97aa44c8783f9f0276ea70854d56f9f6df.tar.bz2 linux-1adddc97aa44c8783f9f0276ea70854d56f9f6df.zip | |
bpf: support epoll from bpf struct_ops links.
Add epoll support to bpf struct_ops links to trigger EPOLLHUP event upon
detachment.
This patch implements the "poll" of the "struct file_operations" for BPF
links and introduces a new "poll" operator in the "struct bpf_link_ops". By
implementing "poll" of "struct bpf_link_ops" for the links of struct_ops,
the file descriptor of a struct_ops link can be added to an epoll file
descriptor to receive EPOLLHUP events.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240530065946.979330-4-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'kernel/bpf/bpf_struct_ops.c')
| -rw-r--r-- | kernel/bpf/bpf_struct_ops.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index 58314b1fc39c..a2cf31b14be4 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -12,6 +12,7 @@ #include <linux/mutex.h> #include <linux/btf_ids.h> #include <linux/rcupdate_wait.h> +#include <linux/poll.h> struct bpf_struct_ops_value { struct bpf_struct_ops_common_value common; @@ -56,6 +57,7 @@ struct bpf_struct_ops_map { struct bpf_struct_ops_link { struct bpf_link link; struct bpf_map __rcu *map; + wait_queue_head_t wait_hup; }; static DEFINE_MUTEX(update_mutex); @@ -1167,15 +1169,28 @@ static int bpf_struct_ops_map_link_detach(struct bpf_link *link) mutex_unlock(&update_mutex); + wake_up_interruptible_poll(&st_link->wait_hup, EPOLLHUP); + return 0; } +static __poll_t bpf_struct_ops_map_link_poll(struct file *file, + struct poll_table_struct *pts) +{ + struct bpf_struct_ops_link *st_link = file->private_data; + + poll_wait(file, &st_link->wait_hup, pts); + + return rcu_access_pointer(st_link->map) ? 0 : EPOLLHUP; +} + static const struct bpf_link_ops bpf_struct_ops_map_lops = { .dealloc = bpf_struct_ops_map_link_dealloc, .detach = bpf_struct_ops_map_link_detach, .show_fdinfo = bpf_struct_ops_map_link_show_fdinfo, .fill_link_info = bpf_struct_ops_map_link_fill_link_info, .update_map = bpf_struct_ops_map_link_update, + .poll = bpf_struct_ops_map_link_poll, }; int bpf_struct_ops_link_create(union bpf_attr *attr) @@ -1208,6 +1223,8 @@ int bpf_struct_ops_link_create(union bpf_attr *attr) if (err) goto err_out; + init_waitqueue_head(&link->wait_hup); + /* Hold the update_mutex such that the subsystem cannot * do link->ops->detach() before the link is fully initialized. */ |