netdev - Re: [FYI][PATCH] tracing/treewide: Remove second parameter of __assign

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: <20240223150339.2249bc95@gandalf.local.home>
Date: Fri, 23 Feb 2024 15:03:39 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Kent Overstreet <kent.overstreet@...ux.dev>
Cc: Jeff Johnson <quic_jjohnson@...cinc.com>, LKML
 <linux-kernel@...r.kernel.org>, Linux Trace Kernel
 <linux-trace-kernel@...r.kernel.org>, Masami Hiramatsu
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 linuxppc-dev@...ts.ozlabs.org, kvm@...r.kernel.org,
 linux-block@...r.kernel.org, linux-cxl@...r.kernel.org,
 linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 amd-gfx@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
 intel-xe@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
 freedreno@...ts.freedesktop.org, virtualization@...ts.linux.dev,
 linux-rdma@...r.kernel.org, linux-pm@...r.kernel.org,
 iommu@...ts.linux.dev, linux-tegra@...r.kernel.org, netdev@...r.kernel.org,
 linux-hyperv@...r.kernel.org, ath10k@...ts.infradead.org,
 linux-wireless@...r.kernel.org, ath11k@...ts.infradead.org,
 ath12k@...ts.infradead.org, brcm80211@...ts.linux.dev,
 brcm80211-dev-list.pdl@...adcom.com, linux-usb@...r.kernel.org,
 linux-bcachefs@...r.kernel.org, linux-nfs@...r.kernel.org,
 ocfs2-devel@...ts.linux.dev, linux-cifs@...r.kernel.org,
 linux-xfs@...r.kernel.org, linux-edac@...r.kernel.org,
 selinux@...r.kernel.org, linux-btrfs@...r.kernel.org,
 linux-erofs@...ts.ozlabs.org, linux-f2fs-devel@...ts.sourceforge.net,
 linux-hwmon@...r.kernel.org, io-uring@...r.kernel.org,
 linux-sound@...r.kernel.org, bpf@...r.kernel.org,
 linux-wpan@...r.kernel.org, dev@...nvswitch.org,
 linux-s390@...r.kernel.org, tipc-discussion@...ts.sourceforge.net, Julia
 Lawall <Julia.Lawall@...ia.fr>
Subject: Re: [FYI][PATCH] tracing/treewide: Remove second parameter of
 __assign_str()

On Fri, 23 Feb 2024 14:50:49 -0500
Kent Overstreet <kent.overstreet@...ux.dev> wrote:

> Tangentially related though, what would make me really happy is if we
> could create the string with in the TP__fast_assign() section. I have to
> have a bunch of annoying wrappers right now because the string length
> has to be known when we invoke the tracepoint.

You can use __string_len() to determine the string length in the tracepoint
(which is executed in the TP_fast_assign() section).

My clean up patches will make __assign_str_len() obsolete too (I'm working
on them now), and you can just use __assign_str().

I noticed that I don't have a string_len example in the sample code and I'm
actually writing it now.

// cutting out everything else:

TRACE_EVENT(foo_bar,

	TP_PROTO(const char *foo, int bar),

	TP_ARGS(foo, bar),

	TP_STRUCT__entry(
		__string_len(	lstr,	foo,	bar < strlen(foo) ? bar : strlen(foo) )
	),

	TP_fast_assign(
		__assign_str(lstr, foo);

// Note, the above is with my updates, without them, you need to duplicate the logic

//		__assign_str_len(lstr, foo, bar < strlen(foo) ? bar : strlen(foo));
	),

	TP_printk("%s", __get_str(lstr))
);


The above will allocate "bar < strlen(foo) ? bar : strlen(foo)" size on the
ring buffer. As the size is already stored, my clean up code uses that
instead of requiring duplicating the logic again.

-- Steve