diff mbox series

[bpf-next,v2,3/8] bpf, iter: Fix the condition on p when calling stop.

Message ID 20220610194435.2268290-4-yosryahmed@google.com (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series bpf: rstat: cgroup hierarchical stats | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR fail PR summary
bpf/vmtest-bpf-next-VM_Test-1 fail Logs for Kernel LATEST on ubuntu-latest with gcc
bpf/vmtest-bpf-next-VM_Test-2 fail Logs for Kernel LATEST on ubuntu-latest with llvm-15
bpf/vmtest-bpf-next-VM_Test-3 fail Logs for Kernel LATEST on z15 with gcc
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 4 this patch: 4
netdev/cc_maintainers success CCed 10 of 10 maintainers
netdev/build_clang success Errors and warnings before: 6 this patch: 6
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 4 this patch: 4
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 11 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Yosry Ahmed June 10, 2022, 7:44 p.m. UTC 
From: Hao Luo <haoluo@google.com>

In bpf_seq_read, seq->op->next() could return an ERR and jump to
the label stop. However, the existing code in stop does not handle
the case when p (returned from next()) is an ERR. Adds the handling
of ERR of p by converting p into an error and jumping to done.

Because all the current implementations do not have a case that
returns ERR from next(), so this patch doesn't have behavior changes
right now.

Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
---
 kernel/bpf/bpf_iter.c | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Yonghong Song June 20, 2022, 6:48 p.m. UTC | #1 
On 6/10/22 12:44 PM, Yosry Ahmed wrote:
> From: Hao Luo <haoluo@google.com>
> 
> In bpf_seq_read, seq->op->next() could return an ERR and jump to
> the label stop. However, the existing code in stop does not handle
> the case when p (returned from next()) is an ERR. Adds the handling
> of ERR of p by converting p into an error and jumping to done.
> 
> Because all the current implementations do not have a case that
> returns ERR from next(), so this patch doesn't have behavior changes
> right now.
> 
> Signed-off-by: Hao Luo <haoluo@google.com>
> Signed-off-by: Yosry Ahmed <yosryahmed@google.com>

Acked-by: Yonghong Song <yhs@fb.com>
Hao Luo June 21, 2022, 7:25 a.m. UTC | #2 
On Mon, Jun 20, 2022 at 11:48 AM Yonghong Song <yhs@fb.com> wrote:
>
> On 6/10/22 12:44 PM, Yosry Ahmed wrote:
> > From: Hao Luo <haoluo@google.com>
> >
> > In bpf_seq_read, seq->op->next() could return an ERR and jump to
> > the label stop. However, the existing code in stop does not handle
> > the case when p (returned from next()) is an ERR. Adds the handling
> > of ERR of p by converting p into an error and jumping to done.
> >
> > Because all the current implementations do not have a case that
> > returns ERR from next(), so this patch doesn't have behavior changes
> > right now.
> >
> > Signed-off-by: Hao Luo <haoluo@google.com>
> > Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
>
> Acked-by: Yonghong Song <yhs@fb.com>

Yonghong, do you want to get this change in now, or you want to wait
for the whole patchset? This fix is straightforward and independent of
other parts. Yosry and I can rebase.
Yonghong Song June 24, 2022, 5:46 p.m. UTC | #3 
On 6/21/22 12:25 AM, Hao Luo wrote:
> On Mon, Jun 20, 2022 at 11:48 AM Yonghong Song <yhs@fb.com> wrote:
>>
>> On 6/10/22 12:44 PM, Yosry Ahmed wrote:
>>> From: Hao Luo <haoluo@google.com>
>>>
>>> In bpf_seq_read, seq->op->next() could return an ERR and jump to
>>> the label stop. However, the existing code in stop does not handle
>>> the case when p (returned from next()) is an ERR. Adds the handling
>>> of ERR of p by converting p into an error and jumping to done.
>>>
>>> Because all the current implementations do not have a case that
>>> returns ERR from next(), so this patch doesn't have behavior changes
>>> right now.
>>>
>>> Signed-off-by: Hao Luo <haoluo@google.com>
>>> Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
>>
>> Acked-by: Yonghong Song <yhs@fb.com>
> 
> Yonghong, do you want to get this change in now, or you want to wait
> for the whole patchset? This fix is straightforward and independent of
> other parts. Yosry and I can rebase.

Sorry for delay. Let me review other patches as well before your next 
version.

BTW, I would be great if you just put the prerequisite patch
 
https://lore.kernel.org/bpf/20220421140740.459558-5-benjamin.tissoires@redhat.com/
as the first patch so at least BPF CI will be able to test
your patch set. It looks like KP's bpf_getxattr patch set already did this.
 
https://lore.kernel.org/bpf/20220624045636.3668195-2-kpsingh@kernel.org/T/#u
Yosry Ahmed June 24, 2022, 6:23 p.m. UTC | #4 
On Fri, Jun 24, 2022 at 10:46 AM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 6/21/22 12:25 AM, Hao Luo wrote:
> > On Mon, Jun 20, 2022 at 11:48 AM Yonghong Song <yhs@fb.com> wrote:
> >>
> >> On 6/10/22 12:44 PM, Yosry Ahmed wrote:
> >>> From: Hao Luo <haoluo@google.com>
> >>>
> >>> In bpf_seq_read, seq->op->next() could return an ERR and jump to
> >>> the label stop. However, the existing code in stop does not handle
> >>> the case when p (returned from next()) is an ERR. Adds the handling
> >>> of ERR of p by converting p into an error and jumping to done.
> >>>
> >>> Because all the current implementations do not have a case that
> >>> returns ERR from next(), so this patch doesn't have behavior changes
> >>> right now.
> >>>
> >>> Signed-off-by: Hao Luo <haoluo@google.com>
> >>> Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
> >>
> >> Acked-by: Yonghong Song <yhs@fb.com>
> >
> > Yonghong, do you want to get this change in now, or you want to wait
> > for the whole patchset? This fix is straightforward and independent of
> > other parts. Yosry and I can rebase.
>
> Sorry for delay. Let me review other patches as well before your next
> version.

Thanks!

>
> BTW, I would be great if you just put the prerequisite patch

I am intending to do that in the next version if KP's patchset doesn't
land in bpf-next.

>
> https://lore.kernel.org/bpf/20220421140740.459558-5-benjamin.tissoires@redhat.com/
> as the first patch so at least BPF CI will be able to test
> your patch set. It looks like KP's bpf_getxattr patch set already did this.
>
> https://lore.kernel.org/bpf/20220624045636.3668195-2-kpsingh@kernel.org/T/#u
>
diff mbox series

Patch

diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c
index d5d96ceca1058..1585caf7c7200 100644
--- a/kernel/bpf/bpf_iter.c
+++ b/kernel/bpf/bpf_iter.c
@@ -198,6 +198,11 @@  static ssize_t bpf_seq_read(struct file *file, char __user *buf, size_t size,
 	}
 stop:
 	offs = seq->count;
+	if (IS_ERR(p)) {
+		seq->op->stop(seq, NULL);
+		err = PTR_ERR(p);
+		goto done;
+	}
 	/* bpf program called if !p */
 	seq->op->stop(seq, p);
 	if (!p) {