Hi! > > > down_read(&triggers_list_lock); > > > down_read(&led_cdev->trigger_lock); > > > > > > - if (!led_cdev->trigger) > > > - len += scnprintf(buf+len, PAGE_SIZE - len, "[none] "); > > > + len = led_trigger_format(NULL, 0, true, led_cdev); > > > + data = kvmalloc(len + 1, GFP_KERNEL); > > > > Why kvmalloc() and not just kmalloc()? How big is this buffer you are > > expecting to have here? > > The ledtrig-cpu supports upto 9999 cpus. If all these cpus were available, > the buffer size would be 78,890 bytes. > (for i in `seq 0 9999`;do echo -n " cpu$i"; done | wc -c) > > The intention of this kvmalloc() allocation is to avoid costly allocation > if possible. Sounds good. > > > - else > > > - len += scnprintf(buf+len, PAGE_SIZE - len, "%s ", > > > - trig->name); > > > - } > > > up_read(&led_cdev->trigger_lock); > > > up_read(&triggers_list_lock); > > > > Two locks? Why not 3? 5? How about just 1? :) > > I don't touch these locks in this patch :) Nor should you :-). > > Just return -ENOMEM above if !data, which makes this much simpler. > > We are holding the two locks, so we need to release them before return. > Which one do you prefer? > > ... > data = kvmalloc(len + 1, GFP_KERNEL); > if (data) > len = led_trigger_format(data, len + 1, false, led_cdev); > else > len = -ENOMEM; > > up_read(&led_cdev->trigger_lock); > up_read(&triggers_list_lock); > > if (len < 0) > return len; > > vs. > > ... > data = kvmalloc(len + 1, GFP_KERNEL); > if (!data) { > up_read(&led_cdev->trigger_lock); > up_read(&triggers_list_lock); > return -ENOMEM; > } > len = led_trigger_format(data, len + 1, false, led_cdev); > > up_read(&led_cdev->trigger_lock); > up_read(&triggers_list_lock); Second one is better. Using goto to jump to error path doing cleanups is also acceptable. Thanks, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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