[PATCH 5.16 0582/1017] libbpf: Unmap rings when umem deleted

Greg Kroah-Hartman
2022-04-05T12:53:05Z

From: lic121 <lic121@chinatelecom.cn>

[ Upstream commit 9c6e6a80ee741adf6cb3cfd8eef7d1554f91fceb ]

xsk_umem__create() does mmap for fill/comp rings, but xsk_umem__delete()
doesn't do the unmap. This works fine for regular cases, because
xsk_socket__delete() does unmap for the rings. But for the case that
xsk_socket__create_shared() fails, umem rings are not unmapped.

fill_save/comp_save are checked to determine if rings have already be
unmapped by xsk. If fill_save and comp_save are NULL, it means that the
rings have already been used by xsk. Then they are supposed to be
unmapped by xsk_socket__delete(). Otherwise, xsk_umem__delete() does the
unmap.

Fixes: 2f6324a3937f ("libbpf: Support shared umems between queues and devices")
Signed-off-by: Cheng Li <lic121@chinatelecom.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220301132623.GA19995@vscode.7~
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/lib/bpf/xsk.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index 81f8fbc85e70..c43b4d94346d 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -1210,12 +1210,23 @@ int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,

int xsk_umem__delete(struct xsk_umem *umem)
{
+ struct xdp_mmap_offsets off;
+ int err;
+
if (!umem)
return 0;

if (umem->refcount)
return -EBUSY;

+ err = xsk_get_mmap_offsets(umem->fd, &off);
+ if (!err && umem->fill_save && umem->comp_save) {
+ munmap(umem->fill_save->ring - off.fr.desc,
+ off.fr.desc + umem->config.fill_size * sizeof(__u64));
+ munmap(umem->comp_save->ring - off.cr.desc,
+ off.cr.desc + umem->config.comp_size * sizeof(__u64));
+ }
+
close(umem->fd);
free(umem);

--
2.34.1