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Message-ID: <173347791315.412.1668780366015175567.tip-bot2@tip-bot2>
Date: Fri, 06 Dec 2024 09:38:33 -0000
From: "tip-bot2 for Andrii Nakryiko" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Andrii Nakryiko <andrii@...nel.org>, Ingo Molnar <mingo@...nel.org>,
Masami Hiramatsu <mhiramat@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
Oleg Nesterov <oleg@...hat.com>, x86@...nel.org, linux-kernel@...r.kernel.org
Subject:
[tip: perf/core] uprobes: Decouple return_instance list traversal and freeing
The following commit has been merged into the perf/core branch of tip:
Commit-ID: fa288f5cfc18bbbe3232d9bacde92acbdb72334f
Gitweb: https://git.kernel.org/tip/fa288f5cfc18bbbe3232d9bacde92acbdb72334f
Author: Andrii Nakryiko <andrii@...nel.org>
AuthorDate: Thu, 05 Dec 2024 16:24:15 -08:00
Committer: Ingo Molnar <mingo@...nel.org>
CommitterDate: Fri, 06 Dec 2024 09:52:01 +01:00
uprobes: Decouple return_instance list traversal and freeing
free_ret_instance() has two unrelated responsibilities: actually
cleaning up return_instance's resources and freeing memory, and also
helping with utask->return_instances list traversal by returning the
next alive pointer.
There is no reason why these two aspects have to be mixed together, so
turn free_ret_instance() into void-returning function and make callers
do list traversal on their own.
We'll use this simplification in the next patch that will guarantee that
to-be-freed return_instance isn't reachable from utask->return_instances
list.
Signed-off-by: Andrii Nakryiko <andrii@...nel.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Link: https://lore.kernel.org/r/20241206002417.3295533-3-andrii@kernel.org
---
kernel/events/uprobes.c | 37 +++++++++++++++++++++----------------
1 file changed, 21 insertions(+), 16 deletions(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 6beac52..cca1fe4 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1888,10 +1888,8 @@ unsigned long uprobe_get_trap_addr(struct pt_regs *regs)
return instruction_pointer(regs);
}
-static struct return_instance *free_ret_instance(struct return_instance *ri, bool cleanup_hprobe)
+static void free_ret_instance(struct return_instance *ri, bool cleanup_hprobe)
{
- struct return_instance *next = ri->next;
-
if (cleanup_hprobe) {
enum hprobe_state hstate;
@@ -1901,7 +1899,6 @@ static struct return_instance *free_ret_instance(struct return_instance *ri, boo
kfree(ri->extra_consumers);
kfree_rcu(ri, rcu);
- return next;
}
/*
@@ -1911,7 +1908,7 @@ static struct return_instance *free_ret_instance(struct return_instance *ri, boo
void uprobe_free_utask(struct task_struct *t)
{
struct uprobe_task *utask = t->utask;
- struct return_instance *ri;
+ struct return_instance *ri, *ri_next;
if (!utask)
return;
@@ -1921,8 +1918,11 @@ void uprobe_free_utask(struct task_struct *t)
timer_delete_sync(&utask->ri_timer);
ri = utask->return_instances;
- while (ri)
- ri = free_ret_instance(ri, true /* cleanup_hprobe */);
+ while (ri) {
+ ri_next = ri->next;
+ free_ret_instance(ri, true /* cleanup_hprobe */);
+ ri = ri_next;
+ }
kfree(utask);
t->utask = NULL;
@@ -2111,12 +2111,15 @@ unsigned long uprobe_get_trampoline_vaddr(void)
static void cleanup_return_instances(struct uprobe_task *utask, bool chained,
struct pt_regs *regs)
{
- struct return_instance *ri = utask->return_instances;
+ struct return_instance *ri = utask->return_instances, *ri_next;
enum rp_check ctx = chained ? RP_CHECK_CHAIN_CALL : RP_CHECK_CALL;
while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) {
- ri = free_ret_instance(ri, true /* cleanup_hprobe */);
+ ri_next = ri->next;
utask->depth--;
+
+ free_ret_instance(ri, true /* cleanup_hprobe */);
+ ri = ri_next;
}
rcu_assign_pointer(utask->return_instances, ri);
}
@@ -2508,7 +2511,7 @@ static struct return_instance *find_next_ret_chain(struct return_instance *ri)
void uprobe_handle_trampoline(struct pt_regs *regs)
{
struct uprobe_task *utask;
- struct return_instance *ri, *next;
+ struct return_instance *ri, *ri_next, *next_chain;
struct uprobe *uprobe;
enum hprobe_state hstate;
bool valid;
@@ -2528,8 +2531,8 @@ void uprobe_handle_trampoline(struct pt_regs *regs)
* or NULL; the latter case means that nobody but ri->func
* could hit this trampoline on return. TODO: sigaltstack().
*/
- next = find_next_ret_chain(ri);
- valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs);
+ next_chain = find_next_ret_chain(ri);
+ valid = !next_chain || arch_uretprobe_is_alive(next_chain, RP_CHECK_RET, regs);
instruction_pointer_set(regs, ri->orig_ret_vaddr);
do {
@@ -2541,7 +2544,9 @@ void uprobe_handle_trampoline(struct pt_regs *regs)
* trampoline addresses on the stack are replaced with correct
* original return addresses
*/
- rcu_assign_pointer(utask->return_instances, ri->next);
+ ri_next = ri->next;
+ rcu_assign_pointer(utask->return_instances, ri_next);
+ utask->depth--;
uprobe = hprobe_consume(&ri->hprobe, &hstate);
if (valid)
@@ -2549,9 +2554,9 @@ void uprobe_handle_trampoline(struct pt_regs *regs)
hprobe_finalize(&ri->hprobe, hstate);
/* We already took care of hprobe, no need to waste more time on that. */
- ri = free_ret_instance(ri, false /* !cleanup_hprobe */);
- utask->depth--;
- } while (ri != next);
+ free_ret_instance(ri, false /* !cleanup_hprobe */);
+ ri = ri_next;
+ } while (ri != next_chain);
} while (!valid);
return;
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