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[198.0.60.179]) by smtp.gmail.com with ESMTPSA id x190sm8140281pfc.89.2019.11.22.09.25.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Nov 2019 09:25:33 -0800 (PST) Date: Fri, 22 Nov 2019 09:25:32 -0800 From: John Fastabend To: Brian Vazquez , Brian Vazquez , Alexei Starovoitov , Daniel Borkmann , "David S . Miller" Cc: Yonghong Song , Stanislav Fomichev , Petar Penkov , Willem de Bruijn , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Brian Vazquez Message-ID: <5dd81a0ca016a_690a2ae784a225c459@john-XPS-13-9370.notmuch> In-Reply-To: <20191119193036.92831-3-brianvv@google.com> References: <20191119193036.92831-1-brianvv@google.com> <20191119193036.92831-3-brianvv@google.com> Subject: RE: [PATCH v2 bpf-next 2/9] bpf: add generic support for lookup and lookup_and_delete batch ops Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Brian Vazquez wrote: > This commit introduces generic support for the bpf_map_lookup_batch and > bpf_map_lookup_and_delete_batch ops. This implementation can be used by > almost all the bpf maps since its core implementation is relying on the > existing map_get_next_key, map_lookup_elem and map_delete_elem > functions. The bpf syscall subcommands introduced are: > > BPF_MAP_LOOKUP_BATCH > BPF_MAP_LOOKUP_AND_DELETE_BATCH > > The UAPI attribute is: > > struct { /* struct used by BPF_MAP_*_BATCH commands */ > __aligned_u64 in_batch; /* start batch, > * NULL to start from beginning > */ > __aligned_u64 out_batch; /* output: next start batch */ > __aligned_u64 keys; > __aligned_u64 values; > __u32 count; /* input/output: > * input: # of key/value > * elements > * output: # of filled elements > */ > __u32 map_fd; > __u64 elem_flags; > __u64 flags; > } batch; > > in_batch/out_batch are opaque values use to communicate between > user/kernel space, in_batch/out_batch must be of key_size length. > > To start iterating from the beginning in_batch must be null, > count is the # of key/value elements to retrieve. Note that the 'keys' > buffer must be a buffer of key_size * count size and the 'values' buffer > must be value_size * count, where value_size must be aligned to 8 bytes > by userspace if it's dealing with percpu maps. 'count' will contain the > number of keys/values successfully retrieved. Note that 'count' is an > input/output variable and it can contain a lower value after a call. > > If there's no more entries to retrieve, ENOENT will be returned. If error > is ENOENT, count might be > 0 in case it copied some values but there were > no more entries to retrieve. > > Note that if the return code is an error and not -EFAULT, > count indicates the number of elements successfully processed. > > Suggested-by: Stanislav Fomichev > Signed-off-by: Brian Vazquez > Signed-off-by: Yonghong Song > --- > include/linux/bpf.h | 11 +++ > include/uapi/linux/bpf.h | 19 +++++ > kernel/bpf/syscall.c | 176 +++++++++++++++++++++++++++++++++++++++ > 3 files changed, 206 insertions(+) > Couple additional comments if we are getting a new rev anyways [...] > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index cc714c9d5b4cc..d0d3d0e0eaca4 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -1127,6 +1127,124 @@ static int map_get_next_key(union bpf_attr *attr) > return err; > } > > +static int __generic_map_lookup_batch(struct bpf_map *map, > + const union bpf_attr *attr, > + union bpf_attr __user *uattr, > + bool do_delete) > +{ > + void __user *ubatch = u64_to_user_ptr(attr->batch.in_batch); > + void __user *uobatch = u64_to_user_ptr(attr->batch.out_batch); > + void __user *values = u64_to_user_ptr(attr->batch.values); > + void __user *keys = u64_to_user_ptr(attr->batch.keys); > + void *buf, *prev_key, *key, *value; > + u32 value_size, cp, max_count; > + bool first_key = false; > + int err, retry = 3; ^^^^^^^^^^ define magic value maybe MAP_LOOKUP_RETRIES > + > + if (attr->batch.elem_flags & ~BPF_F_LOCK) > + return -EINVAL; > + } [...] > + > + value_size = bpf_map_value_size(map); > + > + max_count = attr->batch.count; > + if (!max_count) > + return 0; > + > + err = -ENOMEM; > + buf = kmalloc(map->key_size + value_size, GFP_USER | __GFP_NOWARN); Should we also set __GFP_NORETRY or __GFP_RETRY_MAYFAIL perhaps? > + if (!buf) > + goto err_put; > + > + err = -EFAULT; > + first_key = false; > + if (ubatch && copy_from_user(buf, ubatch, map->key_size)) > + goto free_buf; > + key = buf; > + value = key + map->key_size; > + if (!ubatch) { > + prev_key = NULL; > + first_key = true; > + } > + > + nit: extra newline not needed > + for (cp = 0; cp < max_count; cp++) { > + if (cp || first_key) { > + rcu_read_lock(); > + err = map->ops->map_get_next_key(map, prev_key, key); > + rcu_read_unlock(); > + if (err) > + break; > + } > + err = bpf_map_copy_value(map, key, value, > + attr->batch.elem_flags, do_delete); > + > + if (err == -ENOENT) { > + if (retry) { > + retry--; > + continue; > + } > + err = -EINTR; > + break; > + } > + > + if (err) > + goto free_buf; > + > + if (copy_to_user(keys + cp * map->key_size, key, > + map->key_size)) { > + err = -EFAULT; > + goto free_buf; > + } > + if (copy_to_user(values + cp * value_size, value, value_size)) { > + err = -EFAULT; > + goto free_buf; You could do the same here as in the retry==0 above case, break and report back up to user cp values? > + } > + > + prev_key = key; > + retry = 3; ^^^^^^^^^ same nit as above, use define so we can tune this if needed. > + } > + if (!err) { > + rcu_read_lock(); > + err = map->ops->map_get_next_key(map, prev_key, key); > + rcu_read_unlock(); > + } > + > + if ((copy_to_user(&uattr->batch.count, &cp, sizeof(cp)) || > + (copy_to_user(uobatch, key, map->key_size)))) > + err = -EFAULT; > + > +free_buf: > + kfree(buf); > +err_put: > + return err; > +}