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Re: [PATCH -v5 09/11] tracing: add IRQENTRY_EXIT for MIPS

To: Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: [PATCH -v5 09/11] tracing: add IRQENTRY_EXIT for MIPS
From: Wu Zhangjin <wuzhangjin@gmail.com>
Date: Mon, 26 Oct 2009 15:26:40 +0800
Cc: linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, rostedt@goodmis.org, Thomas Gleixner <tglx@linutronix.de>, Ralf Baechle <ralf@linux-mips.org>, Nicholas Mc Guire <der.herr@hofr.at>, Richard Sandiford <rdsandiford@googlemail.com>, David Daney <ddaney@caviumnetworks.com>, Adam Nemet <anemet@caviumnetworks.com>, Patrik Kluba <kpajko79@gmail.com>
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Organization: DSLab, Lanzhou University, China
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <cover.1256482555.git.wuzhangjin@gmail.com> <2f73eae542c47ac5bbb9f7280e6c0271d193e90d.1256483735.git.wuzhangjin@gmail.com> <3e0c2d7d8b8f196a8153beb41ea7f3cbf42b3d84.1256483735.git.wuzhangjin@gmail.com> <54c417629e91f40b2bbb4e08cda2a4e6527824c0.1256483735.git.wuzhangjin@gmail.com> <29bccff04932e993ecd9f516d8b6dcf84e2ceecf.1256483735.git.wuzhangjin@gmail.com> <72f2270f7b6e01ca7a4cdf4ac8c21778e5d9652f.1256483735.git.wuzhangjin@gmail.com> <6140dd8f4e1783e5ac30977cf008bb98e4698322.1256483735.git.wuzhangjin@gmail.com> <cover.1256483735.git.wuzhangjin@gmail.com> <49b3c441a57f4db423732f81432a3450ccb3240e.1256483735.git.wuzhangjin@gmail.com> <6ad82af0c2ec8ef7b9f536b0a97bf65d385c3945.1256483735.git.wuzhangjin@gmail.com> <c62985530910251736ye7551c4l1a62a1ba242a191f@mail.gmail.com>
Reply-to: wuzhangjin@gmail.com
Sender: linux-mips-bounce@linux-mips.org
Hi,

On Mon, 2009-10-26 at 01:36 +0100, Frederic Weisbecker wrote:
> 2009/10/25 Wu Zhangjin <wuzhangjin@gmail.com>:
> > This patch fix the following error with FUNCTION_GRAPH_TRACER=y:
> >
> > kernel/built-in.o: In function `print_graph_irq':
> > trace_functions_graph.c:(.text+0x6dba0): undefined reference to 
> > `__irqentry_text_start'
> > trace_functions_graph.c:(.text+0x6dba8): undefined reference to 
> > `__irqentry_text_start'
> > trace_functions_graph.c:(.text+0x6dbd0): undefined reference to 
> > `__irqentry_text_end'
> > trace_functions_graph.c:(.text+0x6dbd4): undefined reference to 
> > `__irqentry_text_end'
> >
> > (This patch is need to support function graph tracer of MIPS)
> 
> 
> If you want to enjoy this section, you'd need to tag the
> mips irq entry functions with "__irq_entry"  :)
> 
> I guess there is a do_IRQ() in mips that is waiting for that (and
> probably some others).
> The effect is that interrupt areas are cut with a pair of arrows
> in the trace, so that you more easily spot interrupts in the traces
> 
> May be I missed this part in another patch in this series though...

ooh, Sorry, only this patch added(I stopped after fixing the compiling
errors, no more check! so lazy a guy!).

Just checked the source code of MIPS, the do_IRQ() is defined as a
macro, so, I must move the macro to a C file, and also, there is a
irq_enter...irq_exit block in a "big" function, I need to split it out.

[...]
/*
 * do_IRQ handles all normal device IRQ's (the special
 * SMP cross-CPU interrupts have their own specific
 * handlers).
 *
 * Ideally there should be away to get this into kernel/irq/handle.c to
 * avoid the overhead of a call for just a tiny function ...
 */
#define do_IRQ(irq)
\
do {
\
        irq_enter();
\
        __DO_IRQ_SMTC_HOOK(irq);
\
        generic_handle_irq(irq);
\
        irq_exit();
\
} while (0)
[...]

But The comment told us: do not make this tiny function be a standalone
function, so???

the same to do_IRQ_no_affinity.

and, about the following function, I need to split the
irq_enter()...irq_exit() block out.

void ipi_decode(struct smtc_ipi *pipi)
{
        [...]
        switch (type_copy) {
        case SMTC_CLOCK_TICK:
                irq_enter();
                kstat_incr_irqs_this_cpu(irq, irq_to_desc(irq));
                cd = &per_cpu(mips_clockevent_device, cpu);
                cd->event_handler(cd);
                irq_exit();
                break;

        case LINUX_SMP_IPI:
                switch ((int)arg_copy) {
                case SMP_RESCHEDULE_YOURSELF:
                        ipi_resched_interrupt();
                        break;
                case SMP_CALL_FUNCTION:
                        ipi_call_interrupt();
                        break;
        [...]

Regards,
        Wu Zhangjin


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