Doug / smarc-fsl-linux-kernel

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Commit 91270162bf8a86bee756da7e931591d9953cb5a8

Authored by Tejun Heo
Committed by Greg Kroah-Hartman
1 parent 13c589d5b0
Exists in smarc-imx_3.14.28_1.0.0_ga and in 1 other branch imx_3.14.28_1.0.0_ga

sysfs: skip bin_buffer->buffer while reading 

After b31ca3f5dfc ("sysfs: fix deadlock"), bin read() first writes
data to bb->buffer and bounces it to a transient kernel buffer which
is then copied out to userland.  The double bouncing doesn't add
anything.  Let's just use the transient buffer directly.

While at it, rename @temp to @buf for clarity.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 8 additions and 13 deletions Side-by-side Diff

... ... @@ -72,7 +72,7 @@
72 72 int size = file_inode(file)->i_size;
73 73 loff_t offs = *off;
74 74 int count = min_t(size_t, bytes, PAGE_SIZE);
75   - char *temp;
  75 + char *buf;
76 76  
77 77 if (!bytes)
78 78 return 0;
79 79  
80 80  
81 81  
82 82  
... ... @@ -84,23 +84,18 @@
84 84 count = size - offs;
85 85 }
86 86  
87   - temp = kmalloc(count, GFP_KERNEL);
88   - if (!temp)
  87 + buf = kmalloc(count, GFP_KERNEL);
  88 + if (!buf)
89 89 return -ENOMEM;
90 90  
91 91 mutex_lock(&bb->mutex);
  92 + count = fill_read(file, buf, offs, count);
  93 + mutex_unlock(&bb->mutex);
92 94  
93   - count = fill_read(file, bb->buffer, offs, count);
94   - if (count < 0) {
95   - mutex_unlock(&bb->mutex);
  95 + if (count < 0)
96 96 goto out_free;
97   - }
98 97  
99   - memcpy(temp, bb->buffer, count);
100   -
101   - mutex_unlock(&bb->mutex);
102   -
103   - if (copy_to_user(userbuf, temp, count)) {
  98 + if (copy_to_user(userbuf, buf, count)) {
104 99 count = -EFAULT;
105 100 goto out_free;
106 101 }
... ... @@ -110,7 +105,7 @@
110 105 *off = offs + count;
111 106  
112 107 out_free:
113   - kfree(temp);
  108 + kfree(buf);
114 109 return count;
115 110 }
116 111