[tip: sched/urgent] rseq: Clarify rseq registration rseq_size bound check comment

[tip-bot2 for Mathieu Desnoyers]

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     26d43a90be81fc90e26688a51d3ec83188602731
Gitweb:        https://git.kernel.org/tip/26d43a90be81fc90e26688a51d3ec83188602731
Author:        Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
AuthorDate:    Fri, 20 Feb 2026 15:06:40 -05:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 23 Feb 2026 11:19:19 +01:00

rseq: Clarify rseq registration rseq_size bound check comment

The rseq registration validates that the rseq_size argument is greater
or equal to 32 (the original rseq size), but the comment associated with
this check does not clearly state this.

Clarify the comment to that effect.

Fixes: ee3e3ac05c26 ("rseq: Introduce extensible rseq ABI")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20260220200642.1317826-2-mathieu.desnoyers@xxxxxxxxxxxx
---
 kernel/rseq.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/rseq.c b/kernel/rseq.c
index b0973d1..e349f86 100644
--- a/kernel/rseq.c
+++ b/kernel/rseq.c
@@ -449,8 +449,9 @@ SYSCALL_DEFINE4(rseq, struct rseq __user *, rseq, u32, rseq_len, int, flags, u32
 	 * auxiliary vector AT_RSEQ_ALIGN. If rseq_len is the original rseq
 	 * size, the required alignment is the original struct rseq alignment.
 	 *
-	 * In order to be valid, rseq_len is either the original rseq size, or
-	 * large enough to contain all supported fields, as communicated to
+	 * The rseq_len is required to be greater or equal to the original rseq
+	 * size. In order to be valid, rseq_len is either the original rseq size,
+	 * or large enough to contain all supported fields, as communicated to
 	 * user-space through the ELF auxiliary vector AT_RSEQ_FEATURE_SIZE.
 	 */
 	if (rseq_len < ORIG_RSEQ_SIZE ||