From: Jan Beulich <jbeulich@suse.com>
To: Juergen Gross <jgross@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
George Dunlap <george.dunlap@citrix.com>,
Ian Jackson <iwj@xenproject.org>, Julien Grall <julien@xen.org>,
Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH v2 12/17] xen/hypfs: add new enter() and exit() per node callbacks
Date: Thu, 3 Dec 2020 15:59:54 +0100 [thread overview]
Message-ID: <0c57dd86-36d9-c378-6bdb-50221a7812b8@suse.com> (raw)
In-Reply-To: <20201201082128.15239-13-jgross@suse.com>
On 01.12.2020 09:21, Juergen Gross wrote:
> In order to better support resource allocation and locking for dynamic
> hypfs nodes add enter() and exit() callbacks to struct hypfs_funcs.
>
> The enter() callback is called when entering a node during hypfs user
> actions (traversing, reading or writing it), while the exit() callback
> is called when leaving a node (accessing another node at the same or a
> higher directory level, or when returning to the user).
>
> For avoiding recursion this requires a parent pointer in each node.
> Let the enter() callback return the entry address which is stored as
> the last accessed node in order to be able to use a template entry for
> that purpose in case of dynamic entries.
I guess I'll learn in subsequent patches why this is necessary /
useful. Right now it looks odd for the function to simple return
the incoming argument, as this way it's clear the caller knows
the correct value already.
> @@ -100,11 +112,58 @@ static void hypfs_unlock(void)
> }
> }
>
> +const struct hypfs_entry *hypfs_node_enter(const struct hypfs_entry *entry)
> +{
> + return entry;
> +}
> +
> +void hypfs_node_exit(const struct hypfs_entry *entry)
> +{
> +}
> +
> +static int node_enter(const struct hypfs_entry *entry)
> +{
> + const struct hypfs_entry **last = &this_cpu(hypfs_last_node_entered);
> +
> + entry = entry->funcs->enter(entry);
> + if ( IS_ERR(entry) )
> + return PTR_ERR(entry);
> +
> + ASSERT(!*last || *last == entry->parent);
> +
> + *last = entry;
> +
> + return 0;
> +}
> +
> +static void node_exit(const struct hypfs_entry *entry)
> +{
> + const struct hypfs_entry **last = &this_cpu(hypfs_last_node_entered);
> +
> + if ( !*last )
> + return;
Under what conditions is this legitimate to happen? IOW shouldn't
there be an ASSERT_UNREACHABLE() here?
Jan
next prev parent reply other threads:[~2020-12-03 15:00 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-01 8:21 [PATCH v2 00/17] xen: support per-cpupool scheduling granularity Juergen Gross
2020-12-01 8:21 ` [PATCH v2 01/17] xen/cpupool: add cpu to sched_res_mask when removing it from cpupool Juergen Gross
2020-12-01 8:21 ` [PATCH v2 02/17] xen/cpupool: add missing bits for per-cpupool scheduling granularity Juergen Gross
2020-12-01 8:21 ` [PATCH v2 03/17] xen/cpupool: sort included headers in cpupool.c Juergen Gross
2020-12-01 8:21 ` [PATCH v2 04/17] xen/cpupool: switch cpupool id to unsigned Juergen Gross
2020-12-01 8:55 ` Jan Beulich
2020-12-01 9:01 ` Jürgen Groß
2020-12-01 9:07 ` Jan Beulich
2020-12-07 9:59 ` Jan Beulich
2020-12-07 14:48 ` Jürgen Groß
2020-12-07 15:00 ` Jan Beulich
2020-12-04 15:52 ` Dario Faggioli
2020-12-07 9:58 ` Jan Beulich
2020-12-07 15:21 ` Jan Beulich
2020-12-01 8:21 ` [PATCH v2 05/17] xen/cpupool: switch cpupool list to normal list interface Juergen Gross
2020-12-01 9:12 ` Jan Beulich
2020-12-01 9:18 ` Jürgen Groß
2020-12-04 16:13 ` Dario Faggioli
2020-12-04 16:16 ` Jürgen Groß
2020-12-04 16:25 ` Dario Faggioli
2020-12-04 16:56 ` Dario Faggioli
2020-12-01 8:21 ` [PATCH v2 06/17] xen/cpupool: use ERR_PTR() for returning error cause from cpupool_create() Juergen Gross
2020-12-02 8:58 ` Jan Beulich
2020-12-02 9:56 ` Jürgen Groß
2020-12-02 10:46 ` Jan Beulich
2020-12-02 10:58 ` Jürgen Groß
2020-12-04 16:29 ` Dario Faggioli
2020-12-01 8:21 ` [PATCH v2 07/17] xen/cpupool: support moving domain between cpupools with different granularity Juergen Gross
2020-12-01 8:21 ` [PATCH v2 08/17] docs: fix hypfs path documentation Juergen Gross
2020-12-01 8:21 ` [PATCH v2 09/17] xen/hypfs: move per-node function pointers into a dedicated struct Juergen Gross
2020-12-02 15:36 ` Jan Beulich
2020-12-02 15:41 ` Jürgen Groß
2020-12-03 8:47 ` Jürgen Groß
2020-12-03 9:12 ` Jan Beulich
2020-12-03 9:51 ` Jürgen Groß
2020-12-01 8:21 ` [PATCH v2 10/17] xen/hypfs: pass real failure reason up from hypfs_get_entry() Juergen Gross
2020-12-01 8:21 ` [PATCH v2 11/17] xen/hypfs: add getsize() and findentry() callbacks to hypfs_funcs Juergen Gross
2020-12-02 15:42 ` Jan Beulich
2020-12-02 15:51 ` Jürgen Groß
2020-12-03 8:12 ` Jan Beulich
2020-12-03 9:39 ` Jürgen Groß
2020-12-04 8:58 ` Jan Beulich
2020-12-04 11:14 ` Jürgen Groß
2020-12-01 8:21 ` [PATCH v2 12/17] xen/hypfs: add new enter() and exit() per node callbacks Juergen Gross
2020-12-03 14:59 ` Jan Beulich [this message]
2020-12-03 15:14 ` Jürgen Groß
2020-12-03 15:29 ` Jan Beulich
2020-12-04 8:33 ` Jürgen Groß
2020-12-04 8:30 ` Jan Beulich
2020-12-04 8:35 ` Jürgen Groß
2020-12-01 8:21 ` [PATCH v2 13/17] xen/hypfs: support dynamic hypfs nodes Juergen Gross
2020-12-03 15:08 ` Jan Beulich
2020-12-03 15:18 ` Jürgen Groß
2020-12-01 8:21 ` [PATCH v2 14/17] xen/hypfs: add support for id-based dynamic directories Juergen Gross
2020-12-03 15:44 ` Jan Beulich
2020-12-04 8:52 ` Jürgen Groß
2020-12-04 9:16 ` Jan Beulich
2020-12-04 13:08 ` Jürgen Groß
2020-12-07 7:54 ` Jan Beulich
2020-12-01 8:21 ` [PATCH v2 15/17] xen/cpupool: add cpupool directories Juergen Gross
2020-12-01 9:00 ` Jan Beulich
2020-12-01 9:03 ` Jürgen Groß
2020-12-02 15:46 ` Jürgen Groß
2020-12-03 14:46 ` Jan Beulich
2020-12-03 15:11 ` Jürgen Groß
2020-12-04 9:10 ` Jan Beulich
2020-12-04 11:08 ` Jürgen Groß
2020-12-04 11:54 ` Jan Beulich
2020-12-01 8:21 ` [PATCH v2 16/17] xen/cpupool: add scheduling granularity entry to cpupool entries Juergen Gross
2020-12-01 8:21 ` [PATCH v2 17/17] xen/cpupool: make per-cpupool sched-gran hypfs node writable Juergen Gross
2020-12-04 23:53 ` [PATCH v2 00/17] xen: support per-cpupool scheduling granularity Andrew Cooper
2020-12-05 7:41 ` Jürgen Groß
2020-12-07 9:00 ` Jan Beulich
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