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Date: Tue, 10 May 2022 11:35:03 +0800 From: Tiezhu Yang <yangtiezhu@...ngson.cn> To: davem@...emloft.net, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org> Cc: Xuefeng Li <lixuefeng@...ngson.cn>, netdev@...r.kernel.org, bpf@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCH bpf-next v2 2/2] bpf: Print some info if disable bpf_jit_enable failed A user told me that bpf_jit_enable can be disabled on one system, but he failed to disable bpf_jit_enable on the other system: # echo 0 > /proc/sys/net/core/bpf_jit_enable bash: echo: write error: Invalid argument No useful info is available through the dmesg log, a quick analysis shows that the issue is related with CONFIG_BPF_JIT_ALWAYS_ON. When CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently set to 1 and setting any other value than that will return failure. It is better to print some info to tell the user if disable bpf_jit_enable failed. Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn> --- net/core/sysctl_net_core.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index cf00dd7..ca4527f 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -266,6 +266,8 @@ static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write, loff_t *ppos) { int ret, jit_enable = *(int *)table->data; + int min = *(int *)table->extra1; + int max = *(int *)table->extra2; struct ctl_table tmp = *table; if (write && !capable(CAP_SYS_ADMIN)) @@ -283,6 +285,10 @@ static int proc_dointvec_minmax_bpf_enable(struct ctl_table *table, int write, ret = -EPERM; } } + + if (write && ret && min == max) + pr_info_once("CONFIG_BPF_JIT_ALWAYS_ON is enabled, bpf_jit_enable is permanently set to 1.\n"); + return ret; } -- 2.1.0
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