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From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
To: Song Liu <liu.song.a23@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>,
	srikar@linux.vnet.ibm.com, rostedt@goodmis.org,
	mhiramat@kernel.org, Peter Zijlstra <peterz@infradead.org>,
	mingo@redhat.com, acme@kernel.org,
	alexander.shishkin@linux.intel.com, jolsa@redhat.com,
	namhyung@kernel.org, open list <linux-kernel@vger.kernel.org>,
	corbet@lwn.net, linux-doc@vger.kernel.org,
	ananth@linux.vnet.ibm.com, alexis.berlemont@gmail.com,
	naveen.n.rao@linux.vnet.ibm.com,
	linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org,
	linux@armlinux.org.uk, ralf@linux-mips.org, paul.burton@mips.com,
	Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Subject: Re: [PATCH v5 06/10] Uprobes: Support SDT markers having reference count (semaphore)
Date: Mon, 16 Jul 2018 13:50:10 +0530	[thread overview]
Message-ID: <a37cc94b-5940-643c-3e81-fc375c6aada0@linux.ibm.com> (raw)
In-Reply-To: <CAPhsuW5njYcYXxYYEUsdVWem3qwk2z_bra_eRpwHwEy9TA-LHQ@mail.gmail.com>

Hi Song,

On 07/14/2018 05:20 AM, Song Liu wrote:
> 
> Hmm... what happens when we have multiple uprobes sharing the same
> reference counter? It feels equally complicate to me. Or did I miss any
> cases here?


As far as I can think of, it should be handled by default. No special
treatment needed for this.

...

> 
> This patch tries to resolve this imbalance by passing extra flag
> "restore_insn" to probe_event_disable().
> 
> Signed-off-by: Song Liu <songliubraving@fb.com>


Ah cool. Seems this will make them balanced. But is it fine to change
uprobe_unregister()? It's already an ABI. No other way around?

Also, one more source of imbalance is this condition:

          if (is_register)
                  flags |= VM_WRITE;

in valid_vma(). You need to take care of that as well.

Thanks,
Ravi

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  reply	other threads:[~2018-07-16  8:20 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-28  5:21 [PATCH v5 00/10] Uprobes: Support SDT markers having reference count (semaphore) Ravi Bangoria
2018-06-28  5:22 ` [PATCH v5 01/10] Uprobes: Move uprobe structure to uprobe.h Ravi Bangoria
2018-06-28  5:22 ` [PATCH v5 02/10] Uprobes: Simplify uprobe_register() body Ravi Bangoria
2018-06-28  5:22 ` [PATCH v5 03/10] Uprobe: Change set_swbp definition Ravi Bangoria
2018-06-28  5:22 ` [PATCH v5 04/10] Uprobe: Change set_orig_insn definition Ravi Bangoria
2018-06-28  5:22 ` [PATCH v5 05/10] Uprobe: Change uprobe_write_opcode definition Ravi Bangoria
2018-06-28  5:22 ` [PATCH v5 06/10] Uprobes: Support SDT markers having reference count (semaphore) Ravi Bangoria
2018-06-28 19:51   ` Oleg Nesterov
2018-06-29  3:23     ` Ravi Bangoria
2018-07-01 21:09   ` Oleg Nesterov
2018-07-02  5:16     ` Ravi Bangoria
2018-07-02 18:01       ` Oleg Nesterov
2018-07-03  5:30         ` Ravi Bangoria
2018-07-03  6:16           ` Srikar Dronamraju
2018-07-03  7:43             ` Ravi Bangoria
2018-07-04  9:16               ` Srikar Dronamraju
2018-07-04  9:24                 ` Ravi Bangoria
2018-07-03  8:11           ` Ravi Bangoria
2018-07-03 16:36           ` Oleg Nesterov
2018-07-03 17:25             ` Oleg Nesterov
2018-07-04  4:53               ` Ravi Bangoria
2018-07-10 15:25                 ` Oleg Nesterov
2018-07-11  8:44                   ` Ravi Bangoria
2018-07-11  9:52                     ` Ravi Bangoria
2018-07-12 14:58                     ` Oleg Nesterov
2018-07-12 19:53                       ` Song Liu
2018-07-13  7:55                         ` Ravi Bangoria
2018-07-13 23:50                           ` Song Liu
2018-07-16  8:20                             ` Ravi Bangoria [this message]
2018-07-16  8:51                             ` Ravi Bangoria
2018-07-13  5:39                       ` Ravi Bangoria
2018-07-04  4:49             ` Ravi Bangoria
2018-07-03 17:12           ` Oleg Nesterov
2018-07-03 18:23             ` Oleg Nesterov
2018-07-04  5:25               ` Ravi Bangoria
2018-07-02 16:01   ` Srikar Dronamraju
2018-07-02 18:05     ` Oleg Nesterov
2018-07-03  6:29     ` Ravi Bangoria
2018-07-03 19:26       ` Oleg Nesterov
2018-07-04  5:26         ` Ravi Bangoria
2018-07-04  6:07     ` Ravi Bangoria
2018-06-28  5:22 ` [PATCH v5 07/10] trace_uprobe/sdt: Prevent multiple reference counter for same uprobe Ravi Bangoria
2018-06-28  5:22 ` [PATCH v5 08/10] Uprobes/sdt: " Ravi Bangoria
2018-06-28  5:22 ` [PATCH v5 09/10] Uprobes/sdt: Document about reference counter Ravi Bangoria
2018-07-02 14:54   ` Srikar Dronamraju
2018-07-03  7:50     ` Ravi Bangoria
2018-06-28  5:22 ` [PATCH v5 10/10] perf probe: Support SDT markers having reference counter (semaphore) Ravi Bangoria
2018-07-02 14:45   ` Srikar Dronamraju
2018-07-02 14:57   ` Srikar Dronamraju
2018-07-03  8:00     ` Ravi Bangoria

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