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@xxxxxxxxxxx>
---
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
