Re: [PATCH v3 1/2] tty: hvc: pass DMA capable memory to put_chars()

在 2021/8/5 下午4:09, Jiri Slaby 写道:

On 05. 08. 21, 9:58, Jiri Slaby wrote:

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Hi,

On 04. 08. 21, 4:54, Xianting Tian wrote:

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@@ -933,6 +949,16 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, 

int data,
      hp->outbuf_size = outbuf_size;
      hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];

This deserves cleanup too. Why is "outbuf" not "char outbuf[0] 
__ALIGNED__" at the end of the structure? The allocation would be 
easier (using struct_size()) and this line would be gone completely.

I will make the cleanup in v4.

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+    /*
+     * hvc_con_outbuf is guaranteed to be aligned at least to the
+     * size(N_OUTBUF) by kmalloc().
+     */
+    hp->hvc_con_outbuf = kzalloc(N_OUTBUF, GFP_KERNEL);
+    if (!hp->hvc_con_outbuf)
+        return ERR_PTR(-ENOMEM);

This leaks hp, right?

Actually, why don't you make
char c[N_OUTBUF] __ALIGNED__;

part of struct hvc_struct directly?

thanks, it a good idea, I will change it in v4.

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BTW your 2 patches are still not threaded, that is hard to follow.

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+
+    spin_lock_init(&hp->hvc_con_lock);
+
      tty_port_init(&hp->port);
      hp->port.ops = &hvc_port_ops;

thanks,