Re: [PATCH v7 02/15] swiotlb: Refactor swiotlb_create_debugfs

[Christoph Hellwig]

On Tue, May 18, 2021 at 02:42:02PM +0800, Claire Chang wrote:
>  struct io_tlb_mem *io_tlb_default_mem;
> +static struct dentry *debugfs_dir;
>  
>  /*
>   * Max segment that we can provide which (if pages are contingous) will
> @@ -662,18 +663,30 @@ EXPORT_SYMBOL_GPL(is_swiotlb_active);
>  
>  #ifdef CONFIG_DEBUG_FS
>  
> +static void swiotlb_create_debugfs(struct io_tlb_mem *mem, const char *name)
>  {
>   if (!mem)
> + return;

I don't think this check makes much sense here.

> +}
> +
> +static int __init swiotlb_create_default_debugfs(void)
> +{
> + struct io_tlb_mem *mem = io_tlb_default_mem;
> +
> + if (mem) {
> + swiotlb_create_debugfs(mem, "swiotlb");
> + debugfs_dir = mem->debugfs;
> + } else {
> + debugfs_dir = debugfs_create_dir("swiotlb", NULL);
> + }

This also looks rather strange.  I'd much rather create move the
directory creation of out swiotlb_create_debugfs.  E.g. something like:

static void swiotlb_create_debugfs_file(struct io_tlb_mem *mem)
{
debugfs_create_ulong("io_tlb_nslabs", 0400, mem->debugfs, >nslabs);
debugfs_create_ulong("io_tlb_used", 0400, mem->debugfs, >used);
}

static int __init swiotlb_init_debugfs(void)
{
debugfs_dir = debugfs_create_dir("swiotlb", NULL);
if (io_tlb_default_mem) {
io_tlb_default_mem->debugfs = debugfs_dir;
swiotlb_create_debugfs_files(io_tlb_default_mem);
}
return 0;
}
late_initcall(swiotlb_init_debugfs);

...

static int rmem_swiotlb_device_init(struct reserved_mem *rmem,
struct device *dev)
{
...
mem->debugfs = debugfs_create_dir(rmem->name, debugfs_dir);
swiotlb_create_debugfs_files(mem->debugfs);


}

Re: [PATCH v7 02/15] swiotlb: Refactor swiotlb_create_debugfs

[Florian Fainelli]

On 5/17/2021 11:42 PM, Claire Chang wrote:
> Split the debugfs creation to make the code reusable for supporting
> different bounce buffer pools, e.g. restricted DMA pool.
> 
> Signed-off-by: Claire Chang 

Reviewed-by: Florian Fainelli 
-- 
Florian

[PATCH v7 02/15] swiotlb: Refactor swiotlb_create_debugfs

[Claire Chang]

Split the debugfs creation to make the code reusable for supporting
different bounce buffer pools, e.g. restricted DMA pool.

Signed-off-by: Claire Chang 
---
 kernel/dma/swiotlb.c | 25 +++--
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index d3232fc19385..b849b01a446f 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -64,6 +64,7 @@
 enum swiotlb_force swiotlb_force;
 
 struct io_tlb_mem *io_tlb_default_mem;
+static struct dentry *debugfs_dir;
 
 /*
  * Max segment that we can provide which (if pages are contingous) will
@@ -662,18 +663,30 @@ EXPORT_SYMBOL_GPL(is_swiotlb_active);
 
 #ifdef CONFIG_DEBUG_FS
 
-static int __init swiotlb_create_debugfs(void)
+static void swiotlb_create_debugfs(struct io_tlb_mem *mem, const char *name)
 {
-   struct io_tlb_mem *mem = io_tlb_default_mem;
-
if (!mem)
-   return 0;
-   mem->debugfs = debugfs_create_dir("swiotlb", NULL);
+   return;
+
+   mem->debugfs = debugfs_create_dir(name, debugfs_dir);
debugfs_create_ulong("io_tlb_nslabs", 0400, mem->debugfs, >nslabs);
debugfs_create_ulong("io_tlb_used", 0400, mem->debugfs, >used);
+}
+
+static int __init swiotlb_create_default_debugfs(void)
+{
+   struct io_tlb_mem *mem = io_tlb_default_mem;
+
+   if (mem) {
+   swiotlb_create_debugfs(mem, "swiotlb");
+   debugfs_dir = mem->debugfs;
+   } else {
+   debugfs_dir = debugfs_create_dir("swiotlb", NULL);
+   }
+
return 0;
 }
 
-late_initcall(swiotlb_create_debugfs);
+late_initcall(swiotlb_create_default_debugfs);
 
 #endif
-- 
2.31.1.751.gd2f1c929bd-goog