linux-kernel - Re: [PATCH v3 3/5] RISC-V: Improve init

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Date:   Fri, 09 Apr 2021 13:11:27 +0300
From:   Nick Kossifidis <mick@....forth.gr>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Nick Kossifidis <mick@....forth.gr>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/5] RISC-V: Improve init_resources

Στις 2021-04-06 11:22, Geert Uytterhoeven έγραψε:
> Hi Nick,
> 
> On Tue, Apr 6, 2021 at 10:11 AM Nick Kossifidis <mick@....forth.gr> 
> wrote:
>> Hello Geert,
>> Στις 2021-04-06 10:19, Geert Uytterhoeven έγραψε:
>> > On Mon, Apr 5, 2021 at 10:57 AM Nick Kossifidis <mick@....forth.gr>
>> > wrote:
>> >> * Kernel region is always present and we know where it is, no
>> >> need to look for it inside the loop, just ignore it like the
>> >> rest of the reserved regions within system's memory.
>> >>
>> >> * Don't call memblock_free inside the loop, if called it'll split
>> >> the region of pre-allocated resources in two parts, messing things
>> >> up, just re-use the previous pre-allocated resource and free any
>> >> unused resources after both loops finish.
>> >>
>> >> * memblock_alloc may add a region when called, so increase the
>> >> number of pre-allocated regions by one to be on the safe side
>> >> (reported and patched by Geert Uytterhoeven)
>> >>
>> >> Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
>> >
>> > Where does this SoB come from?
>> >
>> >> Signed-off-by: Nick Kossifidis <mick@....forth.gr>
>> >
>> >> --- a/arch/riscv/kernel/setup.c
>> >> +++ b/arch/riscv/kernel/setup.c
>> >
>> >> @@ -129,53 +139,42 @@ static void __init init_resources(void)
>> >>         struct resource *res = NULL;
>> >>         struct resource *mem_res = NULL;
>> >>         size_t mem_res_sz = 0;
>> >> -       int ret = 0, i = 0;
>> >> -
>> >> -       code_res.start = __pa_symbol(_text);
>> >> -       code_res.end = __pa_symbol(_etext) - 1;
>> >> -       code_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
>> >> -
>> >> -       rodata_res.start = __pa_symbol(__start_rodata);
>> >> -       rodata_res.end = __pa_symbol(__end_rodata) - 1;
>> >> -       rodata_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
>> >> -
>> >> -       data_res.start = __pa_symbol(_data);
>> >> -       data_res.end = __pa_symbol(_edata) - 1;
>> >> -       data_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
>> >> +       int num_resources = 0, res_idx = 0;
>> >> +       int ret = 0;
>> >>
>> >> -       bss_res.start = __pa_symbol(__bss_start);
>> >> -       bss_res.end = __pa_symbol(__bss_stop) - 1;
>> >> -       bss_res.flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
>> >> +       /* + 1 as memblock_alloc() might increase
>> >> memblock.reserved.cnt */
>> >> +       num_resources = memblock.memory.cnt + memblock.reserved.cnt +
>> >> 1;
>> >> +       res_idx = num_resources - 1;
>> >>
>> >> -       mem_res_sz = (memblock.memory.cnt + memblock.reserved.cnt) *
>> >> sizeof(*mem_res);
>> >
>> > Oh, you incorporated my commit ce989f1472ae350e ("RISC-V: Fix
>> > out-of-bounds
>> > accesses in init_resources()") (from v5.12-rc4) into your patch.
>> > Why? This means your patch does not apply against upstream.
>> >
>> 
>> Sorry if this looks awkward, I'm under the impression that new 
>> features
>> go on for-next instead of fixes and your patch hasn't been merged on
>> for-next yet. I thought it would be cleaner to have one patch to merge
>> for init_resources instead of two, and simpler for people to test the
>> series. I can rebase this on top of fixes if that works better for you
>> or Palmer.
> 
> Ideally the fixes branch is part of the next branch.  That also helps
> to avoid other people having to fix conflicts when merging both.
> 

OK I'll re-base this on top of fixes instead.