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From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>
Cc: Jordan Niethe <jniethe5@gmail.com>,
	linuxppc-dev@lists.ozlabs.org,
	Masami Hiramatsu <mhiramat@kernel.org>
Subject: [PATCH 1/5] powerpc/kprobes: Remove preempt disable around call to get_kprobe() in arch_prepare_kprobe()
Date: Thu, 20 Oct 2022 22:58:57 +0530	[thread overview]
Message-ID: <1043d06a0affed83a4a46dd29466e72820ee215d.1666262278.git.naveen.n.rao@linux.vnet.ibm.com> (raw)
In-Reply-To: <cover.1666262278.git.naveen.n.rao@linux.vnet.ibm.com>

arch_prepare_kprobe() is called from register_kprobe() via
prepare_kprobe(), or through register_aggr_kprobe(), both with the
kprobe_mutex held. Per the comment for get_kprobe():
  /*
   * This routine is called either:
   *	- under the 'kprobe_mutex' - during kprobe_[un]register().
   *				OR
   *	- with preemption disabled - from architecture specific code.
   */

As such, there is no need to disable preemption around the call to
get_kprobe(). Drop the same.

Reported-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/kprobes.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index bd7b1a03545948..88f42de681e1f8 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -158,9 +158,7 @@ int arch_prepare_kprobe(struct kprobe *p)
 		printk("Cannot register a kprobe on the second word of prefixed instruction\n");
 		ret = -EINVAL;
 	}
-	preempt_disable();
 	prev = get_kprobe(p->addr - 1);
-	preempt_enable_no_resched();
 
 	/*
 	 * When prev is a ftrace-based kprobe, we don't have an insn, and it
-- 
2.38.0


  reply	other threads:[~2022-10-20 17:31 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-20 17:28 [PATCH 0/5] powerpc/kprobes: preempt related changes and cleanups Naveen N. Rao
2022-10-20 17:28 ` Naveen N. Rao [this message]
2022-11-07 10:14   ` [PATCH 1/5] powerpc/kprobes: Remove preempt disable around call to get_kprobe() in arch_prepare_kprobe() Nicholas Piggin
2022-11-08 10:33     ` Naveen N. Rao
2022-10-20 17:28 ` [PATCH 2/5] powerpc/kprobes: Have optimized_callback() use preempt_enable() Naveen N. Rao
2022-11-07 10:18   ` Nicholas Piggin
2022-10-20 17:28 ` [PATCH 3/5] powerpc/kprobes: Use preempt_enable() rather than the no_resched variant Naveen N. Rao
2022-11-07 10:29   ` Nicholas Piggin
2022-10-20 17:29 ` [PATCH 4/5] powerpc/kprobes: Setup consistent pt_regs across kprobes, optprobes and KPROBES_ON_FTRACE Naveen N. Rao
2022-11-07 11:15   ` Nicholas Piggin
2022-11-08 10:52     ` Naveen N. Rao
2022-10-20 17:29 ` [PATCH 5/5] powerpc/kprobes: Remove unnecessary headers from kprobes Naveen N. Rao
2022-11-02  8:36   ` Christophe Leroy
2022-11-08 10:06     ` Naveen N. Rao
2022-11-07 11:24 ` [PATCH 0/5] powerpc/kprobes: preempt related changes and cleanups Nicholas Piggin
2022-11-30  9:24 ` (subset) " Michael Ellerman

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