> -----Original Message----- > From: Stephen Warren [mailto:swarren@xxxxxxxxxxxxx] > Sent: Wednesday, December 19, 2012 11:08 PM > To: Venu Byravarasu > Cc: balbi@xxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] usb: phy: tegra: Using devm API for memory allocation > > On 12/18/2012 10:38 PM, Venu Byravarasu wrote: > >> -----Original Message----- > >> From: Stephen Warren [mailto:swarren@xxxxxxxxxxxxx] > >> Sent: Tuesday, December 18, 2012 10:03 PM > >> To: Venu Byravarasu > >> Cc: balbi@xxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; linux- > >> kernel@xxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx > >> Subject: Re: [PATCH] usb: phy: tegra: Using devm API for memory > allocation > >> > > > > Stephen, > > As you mentioned I can replace kmalloc with kzalloc in the original code > > and push an updated patch. > > However, I just wanted to understand if there exists any issue > > in using devm_kzalloc instead of kzalloc? > > devm_* are intended for objects allocated during probe(), and free()d > during remove(). The object you're allocating here isn't that case. > > Now, once you convert the Tegra PHY driver to be a true device, perhaps > this object will be allocated/freed during probe/remove, so the devm_ > functions will be useful then? > > The problem this may cause is a memory leak. Consider the Tegra EHCI and > PHY drivers being built as modules, the PHY driver module being inserted > and never removed, yet the EHCI driver being continually inserted and > removed. Since the PHY is never removed, the memory allocated by its > devm_kzalloc() call is never freed, but it's continually re-allocated > since tegra_usb_phy_open() is called whenever the EHCI driver module is > inserted. You need the explicit kfree() to avoid that, and since you're > kfree()ing somewhere other than remove(), using devm_* to make the > allocation isn't appropriate. Thanks Stephen for the detailed explanation. Sent updated patch for review: http://marc.info/?l=linux-usb&m=135599303216132&w=2 . -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
