linux-kernel - Re: [PATCH v2 4/5] blk-iocost: fix sleeping in atomic context warnning

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3da991c6-21e4-8ed8-ba75-ccb92059f0ae@huaweicloud.com>
Date:   Thu, 17 Nov 2022 19:28:50 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     Tejun Heo <tj@...nel.org>, Yu Kuai <yukuai1@...weicloud.com>
Cc:     hch@....de, josef@...icpanda.com, axboe@...nel.dk,
        cgroups@...r.kernel.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, yi.zhang@...wei.com,
        "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH v2 4/5] blk-iocost: fix sleeping in atomic context
 warnning

Hi, Tejun!

在 2022/11/15 6:07, Tejun Heo 写道:

> 
> Any chance I can persuade you into updating match_NUMBER() helpers to not
> use match_strdup()? They can easily disable irq/preemption and use percpu
> buffers and we won't need most of this patchset.

Does the following patch match your proposal?

diff --git a/lib/parser.c b/lib/parser.c
index bcb23484100e..ded652471919 100644
--- a/lib/parser.c
+++ b/lib/parser.c
@@ -11,6 +11,24 @@
  #include <linux/slab.h>
  #include <linux/string.h>

+#define U64_MAX_SIZE 20
+
+static DEFINE_PER_CPU(char, buffer[U64_MAX_SIZE]);
+
+static char *get_buffer(void)
+{
+       preempt_disable();
+       local_irq_disable();
+
+       return this_cpu_ptr(buffer);
+}
+
+static void put_buffer(void)
+{
+       local_irq_enable();
+       preempt_enable();
+}
+

Then match_strdup() and kfree() in match_NUMBER() can be replaced with
get_buffer() and put_buffer().

Thanks,
Kuai
> 
> Thanks.
>