On Sat, May 28, 2011 at 6:29 PM, Robert P. J. Day <[email protected]> wrote: > On Sat, 28 May 2011, Belisko Marek wrote: > >> Hi Robert, >> >> On Sat, May 28, 2011 at 5:15 PM, Robert P. J. Day <[email protected]> >> wrote: >> > >> > from drivers/base/core.c, we have the fairly unambiguous advice: >> > >> > * NOTE: _Never_ directly free @dev after calling this function, even >> > * if it returned an error! Always use put_device() to give up the >> > * reference initialized in this function instead. >> > */ >> > int device_register(struct device *dev) >> > { >> > device_initialize(dev); >> > return device_add(dev); >> > } >> > >> > and yet, there appears to be driver code that does exactly that, >> > such as this snippet from drivers/w1/w1_int.c (line 86): >> > >> > ... snip ... >> > err = device_register(&dev->dev); >> > if (err) { >> > printk(KERN_ERR "Failed to register master device. >> > err=%d\n", err); >> > memset(dev, 0, sizeof(struct w1_master)); >> > kfree(dev); >> > dev = NULL; >> > } >> Free is for allocated dev not for struct device so it is OK. IMO thi >> snippet should look like: >> err = device_register(&dev->dev); >> if (err) { >> printk(KERN_ERR "Failed to register master device. err=%d\n", err); >> put_device(&dev->dev); >> memset(dev, 0, sizeof(struct w1_master)); >> kfree(dev); >> dev = NULL; >> } > > i agree that there should be a "put_device(&dev->dev);" statement as > you show above. however, i still don't see how this can be just a > stylistic improvement as you seem to suggest. based on the warning > from the kernel source file, it would seem that you *must* do a > put_device() in that situation -- it's not optional. Sure you're right. You can send a patch to fix this problem. Good catch. > > rday > > p.s. i would also never do a memset() to zero, followed by a kfree(), > when a kzfree() is so much more concise. > > -- > > ======================================================================== > Robert P. J. Day Ottawa, Ontario, CANADA > http://crashcourse.ca > > Twitter: http://twitter.com/rpjday > LinkedIn: http://ca.linkedin.com/in/rpjday > ========================================================================
regards, marek -- as simple and primitive as possible ------------------------------------------------- Marek Belisko - OPEN-NANDRA Freelance Developer Ruska Nova Ves 219 | Presov, 08005 Slovak Republic Tel: +421 915 052 184 skype: marekwhite icq: 290551086 web: http://open-nandra.com _______________________________________________ Kernelnewbies mailing list [email protected] http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
