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

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Message-Id: <20220405070411.555633168@linuxfoundation.org>
Date:   Tue,  5 Apr 2022 09:24:55 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Cheng Li <lic121@...natelecom.cn>,
        Andrii Nakryiko <andrii@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.16 0582/1017] libbpf: Unmap rings when umem deleted

From: lic121 <lic121@...natelecom.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@...natelecom.cn>
Signed-off-by: Andrii Nakryiko <andrii@...nel.org>
Link: https://lore.kernel.org/bpf/20220301132623.GA19995@vscode.7~
Signed-off-by: Sasha Levin <sashal@...nel.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