linux-kernel - [PATCH v2 4/8] clk: tegra: bpmp: Convert to printbuf

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Date:   Thu, 21 Apr 2022 19:48:33 -0400
From:   Kent Overstreet <kent.overstreet@...il.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org
Cc:     Kent Overstreet <kent.overstreet@...il.com>, hch@....de,
        hannes@...xchg.org, akpm@...ux-foundation.org,
        linux-clk@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-input@...r.kernel.org, roman.gushchin@...ux.dev
Subject: [PATCH v2 4/8] clk: tegra: bpmp: Convert to printbuf

This converts from seq_buf to printbuf, which is similar but heap
allocates the string buffer.

Previously in this code the string buffer was allocated on the stack;
this means we've added a new potential memory allocation failure. This
is fine though since it's only for a dev_printk() message.

Memory allocation context: printbuf doesn't take gfp flags, instead we
prefer the new memalloc_no*_(save|restore) interfaces to be used. Here
the surrounding code is already allocating with GFP_KERNEL, so
everything is fine.

Signed-off-by: Kent Overstreet <kent.overstreet@...il.com>
---
 drivers/clk/tegra/clk-bpmp.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/clk/tegra/clk-bpmp.c b/drivers/clk/tegra/clk-bpmp.c
index 6ecf18f71c..77a8c47806 100644
--- a/drivers/clk/tegra/clk-bpmp.c
+++ b/drivers/clk/tegra/clk-bpmp.c
@@ -5,7 +5,7 @@
 
 #include <linux/clk-provider.h>
 #include <linux/device.h>
-#include <linux/seq_buf.h>
+#include <linux/printbuf.h>
 #include <linux/slab.h>
 
 #include <soc/tegra/bpmp.h>
@@ -360,39 +360,38 @@ static void tegra_bpmp_clk_info_dump(struct tegra_bpmp *bpmp,
 				     const struct tegra_bpmp_clk_info *info)
 {
 	const char *prefix = "";
-	struct seq_buf buf;
+	struct printbuf buf = PRINTBUF;
 	unsigned int i;
-	char flags[64];
-
-	seq_buf_init(&buf, flags, sizeof(flags));
 
 	if (info->flags)
-		seq_buf_printf(&buf, "(");
+		pr_buf(&buf, "(");
 
 	if (info->flags & TEGRA_BPMP_CLK_HAS_MUX) {
-		seq_buf_printf(&buf, "%smux", prefix);
+		pr_buf(&buf, "%smux", prefix);
 		prefix = ", ";
 	}
 
 	if ((info->flags & TEGRA_BPMP_CLK_HAS_SET_RATE) == 0) {
-		seq_buf_printf(&buf, "%sfixed", prefix);
+		pr_buf(&buf, "%sfixed", prefix);
 		prefix = ", ";
 	}
 
 	if (info->flags & TEGRA_BPMP_CLK_IS_ROOT) {
-		seq_buf_printf(&buf, "%sroot", prefix);
+		pr_buf(&buf, "%sroot", prefix);
 		prefix = ", ";
 	}
 
 	if (info->flags)
-		seq_buf_printf(&buf, ")");
+		pr_buf(&buf, ")");
 
 	dev_printk(level, bpmp->dev, "%03u: %s\n", info->id, info->name);
-	dev_printk(level, bpmp->dev, "  flags: %lx %s\n", info->flags, flags);
+	dev_printk(level, bpmp->dev, "  flags: %lx %s\n", info->flags, printbuf_str(&buf));
 	dev_printk(level, bpmp->dev, "  parents: %u\n", info->num_parents);
 
 	for (i = 0; i < info->num_parents; i++)
 		dev_printk(level, bpmp->dev, "    %03u\n", info->parents[i]);
+
+	printbuf_exit(&buf);
 }
 
 static int tegra_bpmp_probe_clocks(struct tegra_bpmp *bpmp,
-- 
2.35.2