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tracing: wprobe: Fix to use IS_ERR_PCPU() for per-cpu pointer

PATCH In review Masami Hiramatsu (Google) 2 participants 3 messages Oct 7, 2025 Tracing

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Masami Hiramatsu (Google)

author maintainer
#0 lore raw

PATCH v2 1/1 tracing: wprobe: Fix to use IS_ERR_PCPU() for per-cpu pointer

From: Masami Hiramatsu (Google) <[email protected]>

Since wprobe uses IS_ERR() for per-cpu pointer, it failed to build.

/tmp/next/build/kernel/trace/trace_wprobe.c: In function '__register_trace_wprobe':
/tmp/next/build/kernel/trace/trace_wprobe.c:176:20: error: cast to generic address space pointer from disjoint '__seg_gs' address space pointer [-Werror]
176 | if (IS_ERR((void * __force)tw->bp_event)) {
| ^
/tmp/next/build/kernel/trace/trace_wprobe.c:177:35: error: cast to generic address space pointer from disjoint '__seg_gs' address space pointer [-Werror]
177 | int ret = PTR_ERR((void * __force)tw->bp_event);
| ^

Use IS_ERR_PCPU() instead.

Reported-by Mark Brown <[email protected]>
Closes https://lore.kernel.org/all/[email protected]/ open here
Suggested-by Linus Torvalds <[email protected]>
Signed-off-by Masami Hiramatsu (Google) <[email protected]>

---
- Confirmed that make allmodconfig && make passed on x86_64 and arm64. Changes in v2:
- Remove unneeded casting.
- Use PTR_ERR_PCPU() too.

---
 kernel/trace/trace_wprobe.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
kernel/trace/trace_wprobe.c +2 -2
index 4b00a8e917c1..98605b207f43 100644
@@ -173,8 +173,8 @@ static int __register_trace_wprobe(struct trace_wprobe *tw)
 	attr.bp_type = tw->type;
 
 	tw->bp_event = register_wide_hw_breakpoint(&attr, wprobe_perf_handler, tw);
-	if (IS_ERR((void * __force)tw->bp_event)) {
-		int ret = PTR_ERR((void * __force)tw->bp_event);
+	if (IS_ERR_PCPU(tw->bp_event)) {
+		int ret = PTR_ERR_PCPU(tw->bp_event);
 
 		tw->bp_event = NULL;
 		return ret;
Reviewed-by on v2 1/1
#1 lore raw
Quoted 32 lines · Masami Hiramatsu (Google)

From: Masami Hiramatsu (Google) <[email protected]>

Since wprobe uses IS_ERR() for per-cpu pointer, it failed to build.

/tmp/next/build/kernel/trace/trace_wprobe.c: In function '__register_trace_wprobe':
/tmp/next/build/kernel/trace/trace_wprobe.c:176:20: error: cast to generic address space pointer from disjoint '__seg_gs' address space pointer [-Werror]
176 | if (IS_ERR((void * __force)tw->bp_event)) {
| ^
/tmp/next/build/kernel/trace/trace_wprobe.c:177:35: error: cast to generic address space pointer from disjoint '__seg_gs' address space pointer [-Werror]
177 | int ret = PTR_ERR((void * __force)tw->bp_event);
| ^

Use IS_ERR_PCPU() instead.

Reported-by Mark Brown <[email protected]>
Closes https://lore.kernel.org/all/[email protected]/ open here
Suggested-by Linus Torvalds <[email protected]>
Signed-off-by Masami Hiramatsu (Google) <[email protected]>

---
- Confirmed that make allmodconfig && make passed on x86_64 and arm64. Changes in v2:
- Remove unneeded casting.
- Use PTR_ERR_PCPU() too.

---
 kernel/trace/trace_wprobe.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
kernel/trace/trace_wprobe.c +0 -0
index 4b00a8e917c1..98605b207f43 100644

kernel/trace/trace_wprobe.c static int __register_trace_wprobe(struct trace_wprobe *tw) · line 177

Quoted 7 lines
kernel/trace/trace_wprobe.c +2 -2
@@ -173,8 +173,8 @@ static int __register_trace_wprobe(struct trace_wprobe *tw)
 	attr.bp_type = tw->type;
 
 	tw->bp_event = register_wide_hw_breakpoint(&attr, wprobe_perf_handler, tw);
-	if (IS_ERR((void * __force)tw->bp_event)) {
-		int ret = PTR_ERR((void * __force)tw->bp_event);
+	if (IS_ERR_PCPU(tw->bp_event)) {
+		int ret = PTR_ERR_PCPU(tw->bp_event);

This version LGTM.

Reviewed-by Menglong Dong <[email protected]>
Quoted 6 lines
kernel/trace/trace_wprobe.c +0 -0
 		tw->bp_event = NULL;
 		return ret;
author maintainer
#2 lore raw
Quoted 43 lines · On Tue, 07 Oct 2025 11:12:18 +0800 Menglong Dong <[email protected]>…
Quoted 32 lines · Masami Hiramatsu (Google)

From: Masami Hiramatsu (Google) <[email protected]>

Since wprobe uses IS_ERR() for per-cpu pointer, it failed to build.

/tmp/next/build/kernel/trace/trace_wprobe.c: In function '__register_trace_wprobe':
/tmp/next/build/kernel/trace/trace_wprobe.c:176:20: error: cast to generic address space pointer from disjoint '__seg_gs' address space pointer [-Werror]
176 | if (IS_ERR((void * __force)tw->bp_event)) {
| ^
/tmp/next/build/kernel/trace/trace_wprobe.c:177:35: error: cast to generic address space pointer from disjoint '__seg_gs' address space pointer [-Werror]
177 | int ret = PTR_ERR((void * __force)tw->bp_event);
| ^

Use IS_ERR_PCPU() instead.

Reported-by Mark Brown <[email protected]>
Closes https://lore.kernel.org/all/[email protected]/ open here
Suggested-by Linus Torvalds <[email protected]>
Signed-off-by Masami Hiramatsu (Google) <[email protected]>

---
- Confirmed that make allmodconfig && make passed on x86_64 and arm64. Changes in v2:
- Remove unneeded casting.
- Use PTR_ERR_PCPU() too.

---
 kernel/trace/trace_wprobe.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
kernel/trace/trace_wprobe.c +0 -0
index 4b00a8e917c1..98605b207f43 100644

kernel/trace/trace_wprobe.c static int __register_trace_wprobe(struct trace_wprobe *tw) · line 177

Quoted 7 lines
kernel/trace/trace_wprobe.c +2 -2
@@ -173,8 +173,8 @@ static int __register_trace_wprobe(struct trace_wprobe *tw)
 	attr.bp_type = tw->type;
 
 	tw->bp_event = register_wide_hw_breakpoint(&attr, wprobe_perf_handler, tw);
-	if (IS_ERR((void * __force)tw->bp_event)) {
-		int ret = PTR_ERR((void * __force)tw->bp_event);
+	if (IS_ERR_PCPU(tw->bp_event)) {
+		int ret = PTR_ERR_PCPU(tw->bp_event);

This version LGTM.

Quoted 1 line
Reviewed-by Menglong Dong <[email protected]>

Thank you! Let me push it in probes/for-next.

Quoted 11 lines
Quoted 7 lines
kernel/trace/trace_wprobe.c +0 -0
 		tw->bp_event = NULL;
 		return ret;
Signature · 1 line
Masami Hiramatsu (Google) <[email protected]>