On 7/10/22 1:19 PM, Matthieu Baerts wrote:
Hi Yonghong,
Thank you for the review!
On 10/07/2022 18:59, Yonghong Song wrote:> On 7/10/22 1:35 AM, Matthieu
Baerts wrote:
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 81b19669efba..2ac424641cc3 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -345,10 +345,10 @@ struct bpf_verifier_state_list {
};
struct bpf_loop_inline_state {
- int initialized:1; /* set to true upon first entry */
- int fit_for_inline:1; /* true if callback function is the same
- * at each call and flags are always zero
- */
+ bool initialized; /* set to true upon first entry */
+ bool fit_for_inline; /* true if callback function is the same
+ * at each call and flags are always zero
+ */
I think changing 'int' to 'unsigned' is a better alternative for
potentially adding more bitfields in the future. This is also a pattern
for many other kernel data structures.
There was room, I was not sure if it would be OK but I saw 'bool' were
often used in structures from this bpf_verifier.h file.
I can of course switch to an unsigned one. I would have picked 'u8' when
looking at the structures around but any preferences from you?
'unsigned', 'unsigned int', 'u8', 'u32'?
The original data structure is
struct bpf_loop_inline_state {
int initialized:1; /* set to true upon first entry */
int fit_for_inline:1; /* true if callback function is the same
* at each call and flags are always zero
*/
u32 callback_subprogno; /* valid when fit_for_inline is true */
};
So 'initialized' and 'fit_for_inline' and additional padding will take
4 bytes, so 'unsigned', 'unsigned int', 'u32' should be appropriate
here. Later, if people want to add a u8 or u16 to utilize the padding,
the type of 'initialized' and 'fit_for_inlined' might be changed to
u8 or u16.
For which of 'unsigned', 'unsigned int', 'u32', checking with
$ [~/work/bpf-next/include/linux] grep ":1" *.h
both 'unsigned' and 'unsigned int' are used in many places. I don't have
a preference. I saw one instance 'unsigned int' is used in this file,
so 'unsigned int' should be okay here.
Cheers,
Matt
