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Merge tag 'ftrace-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

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Pull ftrace update from Steven Rostedt:

 - Speed up ftrace_lookup_symbols() for single lookups

   The kallsyms lookup in ftrace_lookup_symbols() does a linear search
   over each symbol. This is fine when it must match multiple strings,
   but when there's only a single string being searched for, using a
   binary search is much more efficient. When a single string is passed
   in to search, use the binary search method.

* tag 'ftrace-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ftrace: Use kallsyms binary search for single-symbol lookup
This commit is contained in:
Linus Torvalds
2026-04-15 15:57:11 -07:00
parent aec2f682d4 93e8fd1a56
commit 1521829632
1 changed files with 22 additions and 0 deletions
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22
kernel/trace/ftrace.c
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@@ -9267,6 +9267,15 @@ static int kallsyms_callback(void *data, const char *name, unsigned long addr)
* @addrs array, which needs to be big enough to store at least @cnt
* addresses.
*
* For a single symbol (cnt == 1), uses kallsyms_lookup_name() which
* performs an O(log N) binary search via the sorted kallsyms index.
* This avoids the full O(N) linear scan over all kernel symbols that
* the multi-symbol path requires.
*
* For multiple symbols, uses a single-pass linear scan via
* kallsyms_on_each_symbol() with binary search into the sorted input
* array.
*
* Returns: 0 if all provided symbols are found, -ESRCH otherwise.
*/
int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *addrs)
@@ -9274,6 +9283,19 @@ int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *a
struct kallsyms_data args;
int found_all;
/* Fast path: single symbol uses O(log N) binary search */
if (cnt == 1) {
addrs[0] = kallsyms_lookup_name(sorted_syms[0]);
if (addrs[0] && ftrace_location(addrs[0]))
return 0;
/*
* Binary lookup can fail for duplicate symbol names
* where the first match is not ftrace-instrumented.
* Retry with linear scan.
*/
}
/* Batch path: single-pass O(N) linear scan */
memset(addrs, 0, sizeof(*addrs) * cnt);
args.addrs = addrs;
args.syms = sorted_syms;