linux-kernel - Re: [PATCH 59/74] lto: Handle LTO common symbols in module loader

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Date:	Sun, 19 Aug 2012 09:53:02 +0100
From:	"Jan Beulich" <jbeulich@...e.com>
To:	<andi@...stfloor.org>, <ak@...ux.intel.com>,
	<linux-kernel@...r.kernel.org>
Cc:	<x86@...nel.org>, <akpm@...ux-foundation.org>, <jmario@...hat.com>,
	<rusty@...tcorp.com.au>, <mmarek@...e.cz>,
	<linux-kbuild@...r.kernel.org>
Subject: Re: [PATCH 59/74] lto: Handle LTO common symbols in module
 loader

>>> Andi Kleen <andi@...stfloor.org> 08/19/12 4:59 AM >>>
>@@ -1904,6 +1904,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info)
 >
>        switch (sym[i].st_shndx) {
>        case SHN_COMMON:
>+            /* Ignore common symbols */
>+            if (!strncmp(name, "__gnu_lto", 9))
>+                break;
>+
>            /* We compiled with -fno-common.  These are not
>               supposed to happen.  */
>            pr_debug("Common symbol: %s\n", name);

I think it is dangerous to just match the start of the symbol name here -
this may in the future well lead to ignoring symbols we shouldn't be
ignoring.

Also I would think the added comment ought to say "Ignore LTO symbols."
Otherwise its sort of contradicting the purpose of the case being handled
here.

Jan

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