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From: Kent Overstreet <kent.overstreet@gmail.com>
To: Bjorn Helgaas <helgaas@kernel.org>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: linux-kernel@vger.kernel.org, pmladek@suse.com,
	linux-pci@vger.kernel.org
Subject: Re: [PATCH v5 27/32] PCI/P2PDMA: Convert to printbuf
Date: Mon, 8 Aug 2022 14:42:03 -0400	[thread overview]
Message-ID: <1b92761a-c166-b84f-8d77-a966d4c0ef9a@gmail.com> (raw)
In-Reply-To: <20220808175122.GA1215280@bhelgaas>

On 8/8/22 13:51, Bjorn Helgaas wrote:
> I don't object to the patch, but it would be nice if the commit log
> hinted at what the advantage is.  I assume it's faster/safer/better in
> some way, but I have no idea what.

Printbufs have some additional features over seq_buf but they're not 
used here. The main one you might be interested in is heap allocation: 
that means no need to statically allocate buffers on the stack and no 
need to calculate the buffer size, printbufs will reallocate as necessary.

I generally haven't been converting code to use that unless it's obvious 
that we're in a context where it's safe to allocate memory and can deal 
with allocation failures.

I notice that in calc_map_type_and_dist() you're using xa_store() which 
can fail, but you're not checking for that or returning errors properly 
:) perhaps a fix for that could also switch to using printbuf in 
heap-allocation mode.

> Also, cpu_show_meltdown() doesn't appear in this patch, so maybe
> that's relevant to some other patch but not this one?

Whoops, was copying the commit message from another patch, yeah.n

  reply	other threads:[~2022-08-08 18:42 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-08  2:40 [PATCH v5 00/32] Printbufs Matthew Wilcox (Oracle)
2022-08-08  2:40 ` [PATCH v5 01/32] lib/printbuf: New data structure for printing strings Matthew Wilcox (Oracle)
2022-08-08  2:40 ` [PATCH v5 02/32] lib/string_helpers: Convert string_escape_mem() to printbuf Matthew Wilcox (Oracle)
2022-08-08 12:03   ` Andy Shevchenko
2022-08-08 14:58     ` Kent Overstreet
2022-08-08  2:40 ` [PATCH v5 03/32] vsprintf: Convert " Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 04/32] lib/hexdump: " Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 05/32] lib/string_helpers: string_get_size() now returns characters wrote Matthew Wilcox (Oracle)
2022-08-08 13:08   ` Andy Shevchenko
2022-08-08  2:41 ` [PATCH v5 06/32] lib/printbuf: Heap allocation Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 07/32] lib/printbuf: Tabstops, indenting Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 08/32] lib/printbuf: Unit specifiers Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 09/32] vsprintf: Improve number() Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 10/32] vsprintf: prt_u64_minwidth(), prt_u64() Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 11/32] test_printf: Drop requirement that sprintf not write past nul Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 12/32] vsprintf: Start consolidating printf_spec handling Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 13/32] vsprintf: Refactor resource_string() Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 14/32] vsprintf: Refactor fourcc_string() Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 15/32] vsprintf: Refactor ip_addr_string() Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 16/32] vsprintf: Refactor mac_address_string() Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 17/32] vsprintf: time_and_date() no longer takes printf_spec Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 18/32] vsprintf: flags_string() " Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 19/32] vsprintf: Refactor device_node_string, fwnode_string Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 20/32] vsprintf: Refactor hex_string, bitmap_string_list, bitmap_string Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 21/32] Input/joystick/analog: Convert from seq_buf -> printbuf Matthew Wilcox (Oracle)
2022-08-11  1:37   ` Dmitry Torokhov
2022-08-08  2:41 ` [PATCH v5 22/32] mm/memcontrol.c: Convert to printbuf Matthew Wilcox (Oracle)
2022-08-08  9:48   ` Michal Hocko
2022-08-08 12:48     ` Michal Hocko
2022-08-08  2:41 ` [PATCH v5 23/32] clk: tegra: bpmp: " Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 24/32] tools/testing/nvdimm: " Matthew Wilcox (Oracle)
2022-08-08 18:30   ` Dan Williams
2022-08-08 18:33     ` Kent Overstreet
2022-08-08  2:41 ` [PATCH v5 25/32] powerpc: " Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 26/32] x86/resctrl: " Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 27/32] PCI/P2PDMA: " Matthew Wilcox (Oracle)
2022-08-08 17:51   ` Bjorn Helgaas
2022-08-08 18:42     ` Kent Overstreet [this message]
2022-08-09  2:07       ` Bjorn Helgaas
2022-08-09  8:00         ` Christoph Hellwig
2022-08-08  2:41 ` [PATCH v5 28/32] tracing: trace_events_synth: " Matthew Wilcox (Oracle)
2022-08-08  2:41 ` [PATCH v5 29/32] d_path: prt_path() Matthew Wilcox (Oracle)
2022-08-08  4:17   ` Al Viro
2022-08-08  4:27     ` Kent Overstreet
2022-08-08  2:41 ` [PATCH v5 30/32] ACPI/APEI: Add missing include Matthew Wilcox (Oracle)
2022-08-08 14:09   ` Rafael J. Wysocki
2022-08-08  2:41 ` [PATCH v5 31/32] tracing: Convert to printbuf Matthew Wilcox (Oracle)
2022-08-08  2:51   ` Steven Rostedt
2022-08-08  3:32     ` Kent Overstreet
2022-08-08 13:37       ` Steven Rostedt
2022-08-08 15:15         ` Kent Overstreet
2022-08-08 15:25           ` Steven Rostedt
2022-08-08  2:41 ` [PATCH v5 32/32] Delete seq_buf Matthew Wilcox (Oracle)
2022-09-23  7:10 ` [PATCH v5 00/32] Printbufs Petr Mladek
2022-09-24  1:39   ` Kent Overstreet

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