iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

bpf: Print some info if disable bpf_jit_enable failed

Browse Source 
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@loongson.cn>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1652153703-22729-3-git-send-email-yangtiezhu@loongson.cn
This commit is contained in:
Tiezhu Yang 2022-05-10 11:35:03 +08:00 committed by Alexei Starovoitov
parent f922c8972f
commit 174efa7811
1 changed files with 6 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
net/core/sysctl_net_core.c
View File

@ -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;
}