linux-kernel - Re: [PATCH v2 10/16] x86/resctrl: Allocate per-package structures for known events

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Message-ID: <Z-sxsHMF6xvR19wq@agluck-desk3>
Date: Mon, 31 Mar 2025 17:22:08 -0700
From: "Luck, Tony" <tony.luck@...el.com>
To: Reinette Chatre <reinette.chatre@...el.com>
Cc: Fenghua Yu <fenghuay@...dia.com>,
	Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
	Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>, Babu Moger <babu.moger@....com>,
	Drew Fustini <dfustini@...libre.com>,
	Dave Martin <Dave.Martin@....com>, linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev
Subject: Re: [PATCH v2 10/16] x86/resctrl: Allocate per-package structures
 for known events

On Mon, Mar 31, 2025 at 03:23:53PM -0700, Luck, Tony wrote:
> On Mon, Mar 31, 2025 at 09:21:49AM -0700, Reinette Chatre wrote:
> > include/linux/cleanup.h has this to say about mixing goto and free helpers:
> > "convert all resources that need a "goto" cleanup to scope-based cleanup, or convert
> > none of them"
> 
> Seems an awkward restriction for this case. "pkg" is a pointer to
> a dynamic array, and each of the elements of the array might have
> been initialized by another allocation. "pkg" is under control of
> the __free() cleanup function.
> 
> Maybe I could define a custom cleanup (syntax of multi-statement
> action to be figured out):
> 
> DEFINE_FREE(pkg_free, struct pkg_info *,
> 	if (_T)
> 		for (int i = 0; i < num_pkgs; i++)
> 			kfree(_T[i].regions);
> 	kfree(_T)
> )
> 
> 	struct pkg_info *pkg __free(pkg_free) = NULL;

Tried this out and it works (without any odd syntax for the multi-line
action (though I did miss that num_pkgs was a local variable, thankfully
simply initialized from topology_max_packages().


DEFINE_FREE(free_pkg_info, struct pkg_info *,				\
	if (_T)								\
		for (int i = 0; i < topology_max_packages(); i++)	\
			kfree(_T[i].regions);				\
	kfree(_T))

...

	struct pkg_info *pkg __free(free_pkg_info) = NULL;


-Tony