linux-kernel - [PATCH 5.4 151/191] net, sysctl: Fix compiler warning when only cBPF is present

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Message-Id: <20200107205341.050025831@linuxfoundation.org>
Date:   Tue,  7 Jan 2020 21:54:31 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Alexander Lobakin <alobakin@...nk.ru>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH 5.4 151/191] net, sysctl: Fix compiler warning when only cBPF is present

From: Alexander Lobakin <alobakin@...nk.ru>

commit 1148f9adbe71415836a18a36c1b4ece999ab0973 upstream.

proc_dointvec_minmax_bpf_restricted() has been firstly introduced
in commit 2e4a30983b0f ("bpf: restrict access to core bpf sysctls")
under CONFIG_HAVE_EBPF_JIT. Then, this ifdef has been removed in
ede95a63b5e8 ("bpf: add bpf_jit_limit knob to restrict unpriv
allocations"), because a new sysctl, bpf_jit_limit, made use of it.
Finally, this parameter has become long instead of integer with
fdadd04931c2 ("bpf: fix bpf_jit_limit knob for PAGE_SIZE >= 64K")
and thus, a new proc_dolongvec_minmax_bpf_restricted() has been
added.

With this last change, we got back to that
proc_dointvec_minmax_bpf_restricted() is used only under
CONFIG_HAVE_EBPF_JIT, but the corresponding ifdef has not been
brought back.

So, in configurations like CONFIG_BPF_JIT=y && CONFIG_HAVE_EBPF_JIT=n
since v4.20 we have:

  CC      net/core/sysctl_net_core.o
net/core/sysctl_net_core.c:292:1: warning: ‘proc_dointvec_minmax_bpf_restricted’ defined but not used [-Wunused-function]
  292 | proc_dointvec_minmax_bpf_restricted(struct ctl_table *table, int write,
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Suppress this by guarding it with CONFIG_HAVE_EBPF_JIT again.

Fixes: fdadd04931c2 ("bpf: fix bpf_jit_limit knob for PAGE_SIZE >= 64K")
Signed-off-by: Alexander Lobakin <alobakin@...nk.ru>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Link: https://lore.kernel.org/bpf/20191218091821.7080-1-alobakin@dlink.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/core/sysctl_net_core.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -288,6 +288,7 @@ static int proc_dointvec_minmax_bpf_enab
 	return ret;
 }

+# ifdef CONFIG_HAVE_EBPF_JIT
 static int
 proc_dointvec_minmax_bpf_restricted(struct ctl_table *table, int write,
 				    void __user *buffer, size_t *lenp,
@@ -298,6 +299,7 @@ proc_dointvec_minmax_bpf_restricted(stru

 	return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 }
+# endif /* CONFIG_HAVE_EBPF_JIT */

 static int
 proc_dolongvec_minmax_bpf_restricted(struct ctl_table *table, int write,