Star64_linux/kernel/bpf
Eric W. Biederman 66ed594409 bpf/task_iter: In task_file_seq_get_next use task_lookup_next_fd_rcu
When discussing[1] exec and posix file locks it was realized that none
of the callers of get_files_struct fundamentally needed to call
get_files_struct, and that by switching them to helper functions
instead it will both simplify their code and remove unnecessary
increments of files_struct.count.  Those unnecessary increments can
result in exec unnecessarily unsharing files_struct which breaking
posix locks, and it can result in fget_light having to fallback to
fget reducing system performance.

Using task_lookup_next_fd_rcu simplifies task_file_seq_get_next, by
moving the checking for the maximum file descritor into the generic
code, and by remvoing the need for capturing and releasing a reference
on files_struct.  As the reference count of files_struct no longer
needs to be maintained bpf_iter_seq_task_file_info can have it's files
member removed and task_file_seq_get_next no longer needs it's fstruct
argument.

The curr_fd local variable does need to become unsigned to be used
with fnext_task.  As curr_fd is assigned from and assigned a u32
making curr_fd an unsigned int won't cause problems and might prevent
them.

[1] https://lkml.kernel.org/r/20180915160423.GA31461@redhat.com
Suggested-by: Oleg Nesterov <oleg@redhat.com>
v1: https://lkml.kernel.org/r/20200817220425.9389-11-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20201120231441.29911-16-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2020-12-10 12:42:58 -06:00
..
preload bpf: Move prog->aux->linked_prog and trampoline into bpf_link on attach 2020-09-29 13:09:23 -07:00
arraymap.c bpf: Allow for map-in-map with dynamic inner array map entries 2020-10-11 10:21:04 -07:00
bpf_inode_storage.c bpf: Allow specifying a BTF ID per argument in function protos 2020-09-21 15:00:40 -07:00
bpf_iter.c bpf: Bump iter seq size to support BTF representation of large data structures 2020-09-28 18:26:58 -07:00
bpf_local_storage.c bpf: Use hlist_add_head_rcu when linking to local_storage 2020-09-19 01:12:35 +02:00
bpf_lru_list.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206 2019-05-30 11:29:53 -07:00
bpf_lru_list.h bpf: Fix a typo "inacitve" -> "inactive" 2020-04-06 21:54:10 +02:00
bpf_lsm.c bpf: Change bpf_sk_storage_*() to accept ARG_PTR_TO_BTF_ID_SOCK_COMMON 2020-09-25 13:58:01 -07:00
bpf_struct_ops.c bpf: Move btf_resolve_size into __btf_resolve_size 2020-08-25 15:37:41 -07:00
bpf_struct_ops_types.h bpf: tcp: Support tcp_congestion_ops in bpf 2020-01-09 08:46:18 -08:00
btf.c bpf: Introduce bpf_per_cpu_ptr() 2020-10-02 15:00:49 -07:00
cgroup.c Merge branch 'work.set_fs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-22 09:59:21 -07:00
core.c networking changes for the 5.10 merge window 2020-10-15 18:42:13 -07:00
cpumap.c bpf, cpumap: Remove rcpu pointer from cpu_map_build_skb signature 2020-09-28 23:30:42 +02:00
devmap.c bpf: {cpu,dev}map: Change various functions return type from int to void 2020-09-01 15:45:58 +02:00
disasm.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295 2019-06-05 17:36:38 +02:00
disasm.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295 2019-06-05 17:36:38 +02:00
dispatcher.c bpf: Remove bpf_image tree 2020-03-13 12:49:52 -07:00
hashtab.c bpf: Allow for map-in-map with dynamic inner array map entries 2020-10-11 10:21:04 -07:00
helpers.c bpf: Introducte bpf_this_cpu_ptr() 2020-10-02 15:00:49 -07:00
inode.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-09-22 16:45:34 -07:00
local_storage.c bpf/local_storage: Fix build without CONFIG_CGROUP 2020-07-25 20:16:36 -07:00
lpm_trie.c bpf: Add map_meta_equal map ops 2020-08-28 15:41:30 +02:00
Makefile bpf: Implement bpf_local_storage for inodes 2020-08-25 15:00:04 -07:00
map_in_map.c bpf: Relax max_entries check for most of the inner map types 2020-08-28 15:41:30 +02:00
map_in_map.h bpf: Add map_meta_equal map ops 2020-08-28 15:41:30 +02:00
map_iter.c bpf: Implement link_query callbacks in map element iterators 2020-08-21 14:01:39 -07:00
net_namespace.c bpf: Add support for forced LINK_DETACH command 2020-08-01 20:38:28 -07:00
offload.c bpf, offload: Replace bitwise AND by logical AND in bpf_prog_offload_info_fill 2020-02-17 16:53:49 +01:00
percpu_freelist.c bpf: Use raw_spin_trylock() for pcpu_freelist_push/pop in NMI 2020-10-06 00:04:11 +02:00
percpu_freelist.h bpf: Use raw_spin_trylock() for pcpu_freelist_push/pop in NMI 2020-10-06 00:04:11 +02:00
prog_iter.c bpf: Refactor bpf_iter_reg to have separate seq_info member 2020-07-25 20:16:32 -07:00
queue_stack_maps.c bpf: Add map_meta_equal map ops 2020-08-28 15:41:30 +02:00
reuseport_array.c bpf, net: Rework cookie generator as per-cpu one 2020-09-30 11:50:35 -07:00
ringbuf.c bpf: Add map_meta_equal map ops 2020-08-28 15:41:30 +02:00
stackmap.c bpf: Allow specifying a BTF ID per argument in function protos 2020-09-21 15:00:40 -07:00
syscall.c bpf: In bpf_task_fd_query use fget_task 2020-12-10 12:39:44 -06:00
sysfs_btf.c bpf: Fix sysfs export of empty BTF section 2020-09-21 21:50:24 +02:00
task_iter.c bpf/task_iter: In task_file_seq_get_next use task_lookup_next_fd_rcu 2020-12-10 12:42:58 -06:00
tnum.c bpf: Verifier, do explicit ALU32 bounds tracking 2020-03-30 14:59:53 -07:00
trampoline.c bpf: Move prog->aux->linked_prog and trampoline into bpf_link on attach 2020-09-29 13:09:23 -07:00
verifier.c bpf: Enforce id generation for all may-be-null register type 2020-10-19 15:57:42 -07:00