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Message-ID: <20251021133132.29751-1-biancaa2210329@ssn.edu.in>
Date: Tue, 21 Oct 2025 19:01:32 +0530
From: Biancaa Ramesh <biancaa2210329@....edu.in>
To: linux-kernel@...r.kernel.org
Cc: Biancaa Ramesh <biancaa2210329@....edu.in>
Subject: [PATCH] dma-buf: improve dma_buf_show_fdinfo output
dma_buf_show_fdinfo functions into a single function
that prints size, count, flags, attachments, mappings, exp_name, and
name safely with proper spinlock protection for name access.
Signed-off-by: Biancaa Ramesh <biancaa2210329@....edu.in>
---
drivers/dma-buf/dma-buf.c | 49 ++++++++++++++++++++++++---------------
1 file changed, 30 insertions(+), 19 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 2bcf9ceca997..1c0035601c4f 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -394,17 +394,21 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
*/
static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
{
- char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
+ char *name;
- if (IS_ERR(name))
- return PTR_ERR(name);
+ if (!buf)
+ return -EINVAL;
- spin_lock(&dmabuf->name_lock);
- kfree(dmabuf->name);
- dmabuf->name = name;
- spin_unlock(&dmabuf->name_lock);
+ name = strndup_user(buf, DMA_BUF_NAME_LEN);
+ if (IS_ERR(name))
+ return PTR_ERR(name);
- return 0;
+ spin_lock(&dmabuf->name_lock);
+ kfree(dmabuf->name);
+ dmabuf->name = name;
+ spin_unlock(&dmabuf->name_lock);
+
+ return 0;
}
#if IS_ENABLED(CONFIG_SYNC_FILE)
@@ -567,20 +571,27 @@ static long dma_buf_ioctl(struct file *file,
}
}
-static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file)
+static void dma_buf_show_fdinfo(struct seq_file *s, struct file *f)
{
- struct dma_buf *dmabuf = file->private_data;
-
- seq_printf(m, "size:\t%zu\n", dmabuf->size);
- /* Don't count the temporary reference taken inside procfs seq_show */
- seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1);
- seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name);
- spin_lock(&dmabuf->name_lock);
- if (dmabuf->name)
- seq_printf(m, "name:\t%s\n", dmabuf->name);
- spin_unlock(&dmabuf->name_lock);
+ struct dma_buf *dmabuf = f->private_data;
+
+ if (!dmabuf)
+ return;
+
+ seq_printf(s, "flags:\t%lu\n", f->f_flags);
+ seq_printf(s, "size:\t%llu\n", dmabuf->size);
+ seq_printf(s, "count:\t%ld\n", file_count(dmabuf->file) - 1);
+ seq_printf(s, "attachments:\t%d\n", atomic_read(&dmabuf->num_attachments));
+ seq_printf(s, "mappings:\t%d\n", atomic_read(&dmabuf->num_mappings));
+ seq_printf(s, "exp_name:\t%s\n", dmabuf->exp_name ? dmabuf->exp_name : "N/A");
+
+ spin_lock(&dmabuf->name_lock);
+ if (dmabuf->name)
+ seq_printf(s, "name:\t%s\n", dmabuf->name);
+ spin_unlock(&dmabuf->name_lock);
}
+
static const struct file_operations dma_buf_fops = {
.release = dma_buf_file_release,
.mmap = dma_buf_mmap_internal,
--
2.43.0
--
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