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Subject[PATCH] firmware: tegra: reduce stack usage
Date
From: Arnd Bergmann <arnd@arndb.de>

Building the bpmp-debugfs driver for Arm results in a warning for stack usage:

drivers/firmware/tegra/bpmp-debugfs.c:321:16: error: stack frame size of 1224 bytes in function 'bpmp_debug_store' [-Werror,-Wframe-larger-than=]
static ssize_t bpmp_debug_store(struct file *file, const char __user *buf,

It should be possible to rearrange the code to not require two separate
buffers for the file name, but the easiest workaround is to use dynamic
allocation.

Fixes: 5e37b9c137ee ("firmware: tegra: Add support for in-band debug")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/firmware/tegra/bpmp-debugfs.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/tegra/bpmp-debugfs.c b/drivers/firmware/tegra/bpmp-debugfs.c
index 440d99c63638..e1a6b6add180 100644
--- a/drivers/firmware/tegra/bpmp-debugfs.c
+++ b/drivers/firmware/tegra/bpmp-debugfs.c
@@ -74,28 +74,34 @@ static void seqbuf_seek(struct seqbuf *seqbuf, ssize_t offset)
static const char *get_filename(struct tegra_bpmp *bpmp,
const struct file *file, char *buf, int size)
{
- char root_path_buf[512];
+ char *root_path_buf;
const char *root_path;
- const char *filename;
+ const char *filename = NULL;
size_t root_len;

+ root_path_buf = kzalloc(512, GFP_KERNEL);
+ if (!root_path_buf)
+ goto out;
+
root_path = dentry_path(bpmp->debugfs_mirror, root_path_buf,
sizeof(root_path_buf));
if (IS_ERR(root_path))
- return NULL;
+ goto out;

root_len = strlen(root_path);

filename = dentry_path(file->f_path.dentry, buf, size);
if (IS_ERR(filename))
- return NULL;
+ goto out;

if (strlen(filename) < root_len ||
strncmp(filename, root_path, root_len))
- return NULL;
+ goto out;

filename += root_len;

+out:
+ kfree(root_path_buf);
return filename;
}

--
2.27.0
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