linux-kernel - Re: [PATCH v5 06/10] Uprobes: Support SDT markers having reference count (semaphore)

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Message-ID: <20180710152527.GA3616@redhat.com>
Date:   Tue, 10 Jul 2018 17:25:27 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Cc:     srikar@...ux.vnet.ibm.com, rostedt@...dmis.org,
        mhiramat@...nel.org, peterz@...radead.org, mingo@...hat.com,
        acme@...nel.org, alexander.shishkin@...ux.intel.com,
        jolsa@...hat.com, namhyung@...nel.org,
        linux-kernel@...r.kernel.org, corbet@....net,
        linux-doc@...r.kernel.org, ananth@...ux.vnet.ibm.com,
        alexis.berlemont@...il.com, naveen.n.rao@...ux.vnet.ibm.com,
        linux-arm-kernel@...ts.infradead.org, linux-mips@...ux-mips.org,
        linux@...linux.org.uk, ralf@...ux-mips.org, paul.burton@...s.com
Subject: Re: [PATCH v5 06/10] Uprobes: Support SDT markers having reference
 count (semaphore)

Hi Ravi,

On 07/04, Ravi Bangoria wrote:
>
> > Now I understand what did you mean by "for each consumer". So if we move this logic
> > into install/remove_breakpoint as I tried to suggest, we will also need another error
> > code for the case when verify_opcode() returns false.
>
> Ok so if we can use verify_opcode() inside install_breakpoint(), we can probably
> move implementation logic in install/remove_breakpoint(). Let me explore that more.

No, sorry for confusion, I meant another thing... But please forget. If we rely on
verify_opcode() I no longer think it would be more clean to move this logic into
install/remove_breakpoint.

However, I still think it would be better to avoid uprobe exporting and modifying
set_swbp/set_orig_insn. May be we can simply kill both set_swbp() and set_orig_insn(),
I'll re-check...

Oleg.