When hlist_for_each_entry_continue_rcu_bh() gets "next" pointer of
hlist_node structure through rcu_dereference_bh(), sparse warning
appears as the "next" pointer is not annotated as __rcu. So if
the "next" pointer is accessed with hlist_next_rcu() macro, the
__rcu annotation will be added to the pointer. As a consequence,
sparse warning is eliminated too.
The similar errors also appear in hlist_for_each_entry_continue_rcu()
and hlist_for_each_entry_from_rcu().
In this version, CC more people like Paul E. McKenney and lkml mail
list.
Ying Xue (2):
tipc: fix RCU sparse error
ipv6: fix sparse warning
include/linux/rculist.h | 20 ++++++++++----------
net/tipc/name_table.c | 6 +++---
2 files changed, 13 insertions(+), 13 deletions(-)
--
1.7.9.5
The commit 97ede29e80ee ("tipc: convert name table read-write lock to
RCU") involves the following sparse when using
make ARCH=x86_64 allmodconfig
make C=1 CF=-D__CHECK_ENDIAN__
net/tipc/name_table.c:1136:17: sparse: incompatible types in comparison expression (different address spaces)
net/tipc/name_table.c:1136:17: sparse: incompatible types in comparison expression (different address spaces)
To silence above spare complaint, an RCU annotation should be added
to "next" pointer of hlist_node structure through hlist_next_rcu()
macro when iterating over a hlist with hlist_for_each_entry_from_rcu().
By the way, this commit also simplifies the way of dereferencing
the first element of a hlist_head list by replacing
hlist_for_each_entry_rcu() with hlist_entry_safe().
Reported-by: Kbuild test robot <[email protected]>
Cc: Kbuild test robot <[email protected]>
Signed-off-by: Ying Xue <[email protected]>
---
include/linux/rculist.h | 4 ++--
net/tipc/name_table.c | 6 +++---
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index aa79b3c..866d9c9 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -549,8 +549,8 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
*/
#define hlist_for_each_entry_from_rcu(pos, member) \
for (; pos; \
- pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
- typeof(*(pos)), member))
+ pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member))
#endif /* __KERNEL__ */
#endif
diff --git a/net/tipc/name_table.c b/net/tipc/name_table.c
index c8df022..fa4341f 100644
--- a/net/tipc/name_table.c
+++ b/net/tipc/name_table.c
@@ -1110,7 +1110,7 @@ static int __tipc_nl_seq_list(struct tipc_nl_msg *msg, u32 *last_type,
u32 *last_lower, u32 *last_publ)
{
struct hlist_head *seq_head;
- struct name_seq *seq = NULL;
+ struct name_seq *seq;
int err;
int i;
@@ -1127,8 +1127,8 @@ static int __tipc_nl_seq_list(struct tipc_nl_msg *msg, u32 *last_type,
if (!seq)
return -EPIPE;
} else {
- hlist_for_each_entry_rcu(seq, seq_head, ns_list)
- break;
+ seq = hlist_entry_safe(rcu_dereference_raw(
+ hlist_first_rcu(seq_head)), struct name_seq, ns_list);
if (!seq)
continue;
}
--
1.7.9.5
This fixes the following spare warning when using
make C=1 CF=-D__CHECK_ENDIAN__ net/ipv6/addrconf.o
net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
To silence above spare complaint, an RCU annotation should be added
to "next" pointer of hlist_node structure through hlist_next_rcu()
macro when iterating over a hlist with
hlist_for_each_entry_continue_rcu_bh().
By the way, this commit also resolves the same error appearing in
hlist_for_each_entry_continue_rcu().
Signed-off-by: Ying Xue <[email protected]>
---
include/linux/rculist.h | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 866d9c9..32bd4ad 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -524,11 +524,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
* @member: the name of the hlist_node within the struct.
*/
#define hlist_for_each_entry_continue_rcu(pos, member) \
- for (pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
- typeof(*(pos)), member); \
+ for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member); \
pos; \
- pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
- typeof(*(pos)), member))
+ pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member))
/**
* hlist_for_each_entry_continue_rcu_bh - iterate over a hlist continuing after current point
@@ -536,11 +536,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
* @member: the name of the hlist_node within the struct.
*/
#define hlist_for_each_entry_continue_rcu_bh(pos, member) \
- for (pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
- typeof(*(pos)), member); \
+ for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member); \
pos; \
- pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
- typeof(*(pos)), member))
+ pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
+ &(pos)->member)), typeof(*(pos)), member))
/**
* hlist_for_each_entry_from_rcu - iterate over a hlist continuing from current point
--
1.7.9.5
On Wed, Dec 10, 2014 at 04:46:07PM +0800, Ying Xue wrote:
> This fixes the following spare warning when using
>
> make C=1 CF=-D__CHECK_ENDIAN__ net/ipv6/addrconf.o
> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
>
> To silence above spare complaint, an RCU annotation should be added
> to "next" pointer of hlist_node structure through hlist_next_rcu()
> macro when iterating over a hlist with
> hlist_for_each_entry_continue_rcu_bh().
>
> By the way, this commit also resolves the same error appearing in
> hlist_for_each_entry_continue_rcu().
>
> Signed-off-by: Ying Xue <[email protected]>
If you pull the rculist.h changes from the first patch into this one,
I will queue it up through -rcu.
Thanx, Paul
> ---
> include/linux/rculist.h | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/rculist.h b/include/linux/rculist.h
> index 866d9c9..32bd4ad 100644
> --- a/include/linux/rculist.h
> +++ b/include/linux/rculist.h
> @@ -524,11 +524,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
> * @member: the name of the hlist_node within the struct.
> */
> #define hlist_for_each_entry_continue_rcu(pos, member) \
> - for (pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
> - typeof(*(pos)), member); \
> + for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
> + &(pos)->member)), typeof(*(pos)), member); \
> pos; \
> - pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
> - typeof(*(pos)), member))
> + pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
> + &(pos)->member)), typeof(*(pos)), member))
>
> /**
> * hlist_for_each_entry_continue_rcu_bh - iterate over a hlist continuing after current point
> @@ -536,11 +536,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
> * @member: the name of the hlist_node within the struct.
> */
> #define hlist_for_each_entry_continue_rcu_bh(pos, member) \
> - for (pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
> - typeof(*(pos)), member); \
> + for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
> + &(pos)->member)), typeof(*(pos)), member); \
> pos; \
> - pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
> - typeof(*(pos)), member))
> + pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
> + &(pos)->member)), typeof(*(pos)), member))
>
> /**
> * hlist_for_each_entry_from_rcu - iterate over a hlist continuing from current point
> --
> 1.7.9.5
>
From: Ying Xue <[email protected]>
Date: Wed, 10 Dec 2014 16:46:05 +0800
> When hlist_for_each_entry_continue_rcu_bh() gets "next" pointer of
> hlist_node structure through rcu_dereference_bh(), sparse warning
> appears as the "next" pointer is not annotated as __rcu. So if
> the "next" pointer is accessed with hlist_next_rcu() macro, the
> __rcu annotation will be added to the pointer. As a consequence,
> sparse warning is eliminated too.
>
> The similar errors also appear in hlist_for_each_entry_continue_rcu()
> and hlist_for_each_entry_from_rcu().
>
> In this version, CC more people like Paul E. McKenney and lkml mail
> list.
The rculist.h changes should go via Paul's tree, not mine.
On 12/11/2014 12:04 AM, Paul E. McKenney wrote:
> On Wed, Dec 10, 2014 at 04:46:07PM +0800, Ying Xue wrote:
>> This fixes the following spare warning when using
>>
>> make C=1 CF=-D__CHECK_ENDIAN__ net/ipv6/addrconf.o
>> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
>> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
>> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
>> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
>>
>> To silence above spare complaint, an RCU annotation should be added
>> to "next" pointer of hlist_node structure through hlist_next_rcu()
>> macro when iterating over a hlist with
>> hlist_for_each_entry_continue_rcu_bh().
>>
>> By the way, this commit also resolves the same error appearing in
>> hlist_for_each_entry_continue_rcu().
>>
>> Signed-off-by: Ying Xue <[email protected]>
>
> If you pull the rculist.h changes from the first patch into this one,
> I will queue it up through -rcu.
>
Please just queue this patch into your RCU tree. Some changes of the
first patch currently only exists in net-next tree, so it cannot be
merged into RCU tree now. Therefore, please temporarily ignore it. In
next 3.19 development cycle, I will resubmit it to you.
Thanks,
Ying
> Thanx, Paul
>
>> ---
>> include/linux/rculist.h | 16 ++++++++--------
>> 1 file changed, 8 insertions(+), 8 deletions(-)
>>
>> diff --git a/include/linux/rculist.h b/include/linux/rculist.h
>> index 866d9c9..32bd4ad 100644
>> --- a/include/linux/rculist.h
>> +++ b/include/linux/rculist.h
>> @@ -524,11 +524,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
>> * @member: the name of the hlist_node within the struct.
>> */
>> #define hlist_for_each_entry_continue_rcu(pos, member) \
>> - for (pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
>> - typeof(*(pos)), member); \
>> + for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
>> + &(pos)->member)), typeof(*(pos)), member); \
>> pos; \
>> - pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
>> - typeof(*(pos)), member))
>> + pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
>> + &(pos)->member)), typeof(*(pos)), member))
>>
>> /**
>> * hlist_for_each_entry_continue_rcu_bh - iterate over a hlist continuing after current point
>> @@ -536,11 +536,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
>> * @member: the name of the hlist_node within the struct.
>> */
>> #define hlist_for_each_entry_continue_rcu_bh(pos, member) \
>> - for (pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
>> - typeof(*(pos)), member); \
>> + for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
>> + &(pos)->member)), typeof(*(pos)), member); \
>> pos; \
>> - pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
>> - typeof(*(pos)), member))
>> + pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
>> + &(pos)->member)), typeof(*(pos)), member))
>>
>> /**
>> * hlist_for_each_entry_from_rcu - iterate over a hlist continuing from current point
>> --
>> 1.7.9.5
>>
>
>
>
On Thu, Dec 11, 2014 at 09:56:33AM +0800, Ying Xue wrote:
> On 12/11/2014 12:04 AM, Paul E. McKenney wrote:
> > On Wed, Dec 10, 2014 at 04:46:07PM +0800, Ying Xue wrote:
> >> This fixes the following spare warning when using
> >>
> >> make C=1 CF=-D__CHECK_ENDIAN__ net/ipv6/addrconf.o
> >> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
> >> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
> >> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
> >> net/ipv6/addrconf.c:3495:9: error: incompatible types in comparison expression (different address spaces)
> >>
> >> To silence above spare complaint, an RCU annotation should be added
> >> to "next" pointer of hlist_node structure through hlist_next_rcu()
> >> macro when iterating over a hlist with
> >> hlist_for_each_entry_continue_rcu_bh().
> >>
> >> By the way, this commit also resolves the same error appearing in
> >> hlist_for_each_entry_continue_rcu().
> >>
> >> Signed-off-by: Ying Xue <[email protected]>
> >
> > If you pull the rculist.h changes from the first patch into this one,
> > I will queue it up through -rcu.
>
> Please just queue this patch into your RCU tree. Some changes of the
> first patch currently only exists in net-next tree, so it cannot be
> merged into RCU tree now. Therefore, please temporarily ignore it. In
> next 3.19 development cycle, I will resubmit it to you.
Sounds good, but could you please rebase the second patch to be
independent of the first patch? If you do that, I would be happy
to queue it.
Thanx, Paul
> Thanks,
> Ying
>
> > Thanx, Paul
> >
> >> ---
> >> include/linux/rculist.h | 16 ++++++++--------
> >> 1 file changed, 8 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/include/linux/rculist.h b/include/linux/rculist.h
> >> index 866d9c9..32bd4ad 100644
> >> --- a/include/linux/rculist.h
> >> +++ b/include/linux/rculist.h
> >> @@ -524,11 +524,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
> >> * @member: the name of the hlist_node within the struct.
> >> */
> >> #define hlist_for_each_entry_continue_rcu(pos, member) \
> >> - for (pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
> >> - typeof(*(pos)), member); \
> >> + for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
> >> + &(pos)->member)), typeof(*(pos)), member); \
> >> pos; \
> >> - pos = hlist_entry_safe(rcu_dereference((pos)->member.next),\
> >> - typeof(*(pos)), member))
> >> + pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu( \
> >> + &(pos)->member)), typeof(*(pos)), member))
> >>
> >> /**
> >> * hlist_for_each_entry_continue_rcu_bh - iterate over a hlist continuing after current point
> >> @@ -536,11 +536,11 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
> >> * @member: the name of the hlist_node within the struct.
> >> */
> >> #define hlist_for_each_entry_continue_rcu_bh(pos, member) \
> >> - for (pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
> >> - typeof(*(pos)), member); \
> >> + for (pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
> >> + &(pos)->member)), typeof(*(pos)), member); \
> >> pos; \
> >> - pos = hlist_entry_safe(rcu_dereference_bh((pos)->member.next),\
> >> - typeof(*(pos)), member))
> >> + pos = hlist_entry_safe(rcu_dereference_bh(hlist_next_rcu( \
> >> + &(pos)->member)), typeof(*(pos)), member))
> >>
> >> /**
> >> * hlist_for_each_entry_from_rcu - iterate over a hlist continuing from current point
> >> --
> >> 1.7.9.5
> >>
> >
> >
> >
>