On 8/18/20 5:23 PM, Martin KaFai Lau wrote: > On Tue, Aug 18, 2020 at 05:10:34PM +0200, KP Singh wrote: >> >> >> On 8/18/20 3:27 AM, Martin KaFai Lau wrote:>>> On Mon, Aug 03, 2020 at 06:46:53PM +0200, KP Singh wrote: [...] a get_file >> rather fcheck followed by get_file_rcu: >> >> #define get_file_rcu_many(x, cnt) \ >> atomic_long_add_unless(&(x)->f_count, (cnt), 0) >> #define get_file_rcu(x) get_file_rcu_many((x), 1) >> #define file_count(x) atomic_long_read(&(x)->f_count) >> >> But there is an easier way than all of this and this is to use >> fget_raw which also calls get_file_rcu_many >> and ensures a non-zero count before getting a reference. > ic. Make sense. > > There are fdget() and fdput() also which are used in bpf/syscall.c. Yeah we could use fdget_raw but we don't really need the struct fd but just the struct file. he non-raw versions masks away FMODE_PATH (O_PATH) files, we should still be able to access blobs on the O_PATH files, thus the _raw version here. - KP >
