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perf: Remove get_perf_callchain() init_nr argument

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The 'init_nr' argument has double duty: it's used to initialize both the
number of contexts and the number of stack entries.  That's confusing
and the callers always pass zero anyway.  Hard code the zero.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Namhyung Kim <Namhyung@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20250820180428.259565081@kernel.org
This commit is contained in:
Josh Poimboeuf
2025-08-20 14:03:39 -04:00
committed by Peter Zijlstra
parent f49e1be195
commit e649bcda25
4 changed files with 10 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/perf_event.h
View File

@@ -1719,7 +1719,7 @@ DECLARE_PER_CPU(struct perf_callchain_entry, perf_callchain_entry);
extern void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs);
extern void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs);
extern struct perf_callchain_entry *
get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
u32 max_stack, bool crosstask, bool add_mark);
extern int get_callchain_buffers(int max_stack);
extern void put_callchain_buffers(void);

4
kernel/bpf/stackmap.c
View File

@@ -314,7 +314,7 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
if (max_depth > sysctl_perf_event_max_stack)
max_depth = sysctl_perf_event_max_stack;
trace = get_perf_callchain(regs, 0, kernel, user, max_depth,
trace = get_perf_callchain(regs, kernel, user, max_depth,
false, false);
if (unlikely(!trace))
@@ -451,7 +451,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
else if (kernel && task)
trace = get_callchain_entry_for_task(task, max_depth);
else
trace = get_perf_callchain(regs, 0, kernel, user, max_depth,
trace = get_perf_callchain(regs, kernel, user, max_depth,
crosstask, false);
if (unlikely(!trace) || trace->nr < skip) {

12
kernel/events/callchain.c
View File

@@ -217,7 +217,7 @@ static void fixup_uretprobe_trampoline_entries(struct perf_callchain_entry *entr
}
struct perf_callchain_entry *
get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
u32 max_stack, bool crosstask, bool add_mark)
{
struct perf_callchain_entry *entry;
@@ -228,11 +228,11 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
if (!entry)
return NULL;
ctx.entry = entry;
ctx.max_stack = max_stack;
ctx.nr = entry->nr = init_nr;
ctx.contexts = 0;
ctx.contexts_maxed = false;
ctx.entry = entry;
ctx.max_stack = max_stack;
ctx.nr = entry->nr = 0;
ctx.contexts = 0;
ctx.contexts_maxed = false;
if (kernel && !user_mode(regs)) {
if (add_mark)

2
kernel/events/core.c
View File

@@ -8210,7 +8210,7 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs)
if (!kernel && !user)
return &__empty_callchain;
callchain = get_perf_callchain(regs, 0, kernel, user,
callchain = get_perf_callchain(regs, kernel, user,
max_stack, crosstask, true);
return callchain ?: &__empty_callchain;
}