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uprobes: kill the unnecessary put_uprobe/xol_free_insn_slot in uprobe_free_utask()

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If pre_ssout() succeeds and sets utask->active_uprobe and utask->xol_vaddr
the task must not exit until it calls handle_singlestep() which does the
necessary put_uprobe() and xol_free_insn_slot().

Remove put_uprobe() and xol_free_insn_slot() from uprobe_free_utask(). With
this change xol_free_insn_slot() can't hit xol_area/utask/xol_vaddr == NULL,
we can kill the unnecessary checks checks and simplify this function more.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240929144239.GA9475@redhat.com
This commit is contained in:
Oleg Nesterov 2024-09-29 16:42:39 +02:00 committed by Peter Zijlstra
parent c7b4133c48
commit 430af825ba
1 changed files with 5 additions and 19 deletions
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24
kernel/events/uprobes.c
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@ -1673,28 +1673,16 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe)
}
/*
* xol_free_insn_slot - If slot was earlier allocated by
* @xol_get_insn_slot(), make the slot available for
* subsequent requests.
* xol_free_insn_slot - free the slot allocated by xol_get_insn_slot()
*/
static void xol_free_insn_slot(struct task_struct *tsk)
{
struct xol_area *area;
unsigned long slot_addr;
unsigned long offset;
if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask)
return;
slot_addr = tsk->utask->xol_vaddr;
if (unlikely(!slot_addr))
return;
struct xol_area *area = tsk->mm->uprobes_state.xol_area;
unsigned long offset = tsk->utask->xol_vaddr - area->vaddr;
tsk->utask->xol_vaddr = 0;
area = tsk->mm->uprobes_state.xol_area;
offset = slot_addr - area->vaddr;
/*
* slot_addr must fit into [area->vaddr, area->vaddr + PAGE_SIZE).
* xol_vaddr must fit into [area->vaddr, area->vaddr + PAGE_SIZE).
* This check can only fail if the "[uprobes]" vma was mremap'ed.
*/
if (offset < PAGE_SIZE) {
@ -1764,14 +1752,12 @@ void uprobe_free_utask(struct task_struct *t)
if (!utask)
return;
if (utask->active_uprobe)
put_uprobe(utask->active_uprobe);
WARN_ON_ONCE(utask->active_uprobe || utask->xol_vaddr);
ri = utask->return_instances;
while (ri)
ri = free_ret_instance(ri);
xol_free_insn_slot(t);
kfree(utask);
t->utask = NULL;
}