[tip: perf/core] uprobes: move the initialization of utask->xol_vaddr from pre_ssout() to xol_get_insn_slot()

[tip-bot2 for Oleg Nesterov]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     1cee988c1d21eabc936d1401811012522083e36f
Gitweb:        https://git.kernel.org/tip/1cee988c1d21eabc936d1401811012522083e36f
Author:        Oleg Nesterov <oleg@xxxxxxxxxx>
AuthorDate:    Sun, 29 Sep 2024 16:42:48 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 07 Oct 2024 09:28:45 +02:00

uprobes: move the initialization of utask->xol_vaddr from pre_ssout() to xol_get_insn_slot()

This simplifies the code and makes xol_get_insn_slot() symmetric with
xol_free_insn_slot() which clears utask->xol_vaddr.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240929144248.GA9483@xxxxxxxxxx
---
 kernel/events/uprobes.c | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 616b5ff..dfaca30 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1646,21 +1646,19 @@ static unsigned long xol_take_insn_slot(struct xol_area *area)
 
 /*
  * xol_get_insn_slot - allocate a slot for xol.
- * Returns the allocated slot address or 0.
  */
-static unsigned long xol_get_insn_slot(struct uprobe *uprobe)
+static bool xol_get_insn_slot(struct uprobe *uprobe)
 {
-	struct xol_area *area;
-	unsigned long xol_vaddr;
+	struct uprobe_task *utask = current->utask;
+	struct xol_area *area = get_xol_area();
 
-	area = get_xol_area();
 	if (!area)
-		return 0;
+		return false;
 
-	xol_vaddr = xol_take_insn_slot(area);
-	arch_uprobe_copy_ixol(area->page, xol_vaddr,
+	utask->xol_vaddr = xol_take_insn_slot(area);
+	arch_uprobe_copy_ixol(area->page, utask->xol_vaddr,
 			      &uprobe->arch.ixol, sizeof(uprobe->arch.ixol));
-	return xol_vaddr;
+	return true;
 }
 
 /*
@@ -1948,21 +1946,17 @@ static int
 pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
 {
 	struct uprobe_task *utask = current->utask;
-	unsigned long xol_vaddr;
 	int err;
 
 	if (!try_get_uprobe(uprobe))
 		return -EINVAL;
 
-	xol_vaddr = xol_get_insn_slot(uprobe);
-	if (!xol_vaddr) {
+	if (!xol_get_insn_slot(uprobe)) {
 		err = -ENOMEM;
 		goto err_out;
 	}
 
-	utask->xol_vaddr = xol_vaddr;
 	utask->vaddr = bp_vaddr;
-
 	err = arch_uprobe_pre_xol(&uprobe->arch, regs);
 	if (unlikely(err)) {
 		xol_free_insn_slot(current);