Hello Sahitya Tummala,
The patch 4cff6d991e4a: "ufs: Add freq-table-hz property for UFS
device" from Sep 25, 2014, leads to the following static checker
warning:
drivers/scsi/ufs/ufshcd-pltfrm.c:138 ufshcd_parse_clock_info()
warn: passing devm_ allocated variable to kfree. 'clkfreq'
drivers/scsi/ufs/ufshcd-pltfrm.c
102 clkfreq = devm_kzalloc(dev, sz * sizeof(*clkfreq),
103 GFP_KERNEL);
^^^^^^^^^^^^^
104 if (!clkfreq) {
105 dev_err(dev, "%s: no memory\n", "freq-table-hz");
Don't print an error. It just wastes ram. Error messages are often
buggy. If we delete it then the code is shorter and easier to read.
Kmalloc() has its own more useful error message already.
106 ret = -ENOMEM;
107 goto out;
Out labels are the worst. The name is too vague. They are a sign of
either One Err type error handling where you have one label handle
everything or they are a just a do-nothing goto where it returns
directly.
One Err type error handling causes bugs.
Do-nothing gotos are just annoying. You're reading the code and you see
a "goto out;" and you think "What does "out" do?" But the name doesn't
provide any hints. You scroll down to the bottom of the function. "Oh
it was just a waste of time." Now you have lost your place and your
train of thought.
Also people constantly forget to set "ret" before the goto out. If you
just write:
if (!of_get_property(np, "freq-table-hz", &len)) {
dev_info(dev, "freq-table-hz property not specified\n");
return 0;
}
if (len <= 0)
return 0;
Then it's totally clear what we intended to return. But in the current
code it's ambiguous because maybe we just forgot to set ret? Who
knows. Out labels make the code hard to understand.
Anyway, in this case, originally "out" was doing One Err error handling
but now it's just there to waste our time and cause bugs when this code
is modified in the future.
108 }
109
110 ret = of_property_read_u32_array(np, "freq-table-hz",
111 clkfreq, sz);
112 if (ret && (ret != -EINVAL)) {
113 dev_err(dev, "%s: error reading array %d\n",
114 "freq-table-hz", ret);
115 goto free_clkfreq;
116 }
117
118 for (i = 0; i < sz; i += 2) {
119 ret = of_property_read_string_index(np,
120 "clock-names", i/2, (const char **)&name);
121 if (ret)
122 goto free_clkfreq;
123
124 clki = devm_kzalloc(dev, sizeof(*clki), GFP_KERNEL);
125 if (!clki) {
126 ret = -ENOMEM;
127 goto free_clkfreq;
128 }
129
130 clki->min_freq = clkfreq[i];
131 clki->max_freq = clkfreq[i+1];
132 clki->name = kstrdup(name, GFP_KERNEL);
Where is name freed? There are definitely certain error paths where it
is leaked. Can we use devm_kstrdup() here?
133 dev_dbg(dev, "%s: min %u max %u name %s\n", "freq-table-hz",
134 clki->min_freq, clki->max_freq, clki->name);
135 list_add_tail(&clki->list, &hba->clk_list_head);
136 }
137 free_clkfreq:
138 kfree(clkfreq);
^^^^^^^^^^^^^
Just delete this.
139 out:
140 return ret;
141 }
regards,
dan carpenter
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