From: Tiezhu Yang Date: Tue, 10 May 2022 03:35:03 +0000 (+0800) Subject: bpf: Print some info if disable bpf_jit_enable failed X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=174efa7811659b3e3dec05b3649dc6d66c8c4628;p=linux.git 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 Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/1652153703-22729-3-git-send-email-yangtiezhu@loongson.cn --- diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index cf00dd7d46d70..ca4527fcbc758 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; }