On Thu, 2017-10-12 at 13:16 +1100, Tobin C. Harding wrote: > On Wed, Oct 11, 2017 at 06:02:47PM +0530, Shreeya Patel wrote: > > > > On Tue, 2017-10-10 at 11:06 +1100, Tobin C. Harding wrote: > > > > > > On Tue, Oct 10, 2017 at 02:48:58AM +0530, Shreeya Patel wrote: > > > > > > > > > > > > Remove NULL pointer dereference as it results in undefined > > > > behaviour, and will usually lead to a runtime error. > > > The diff does not show any pointer dereference so it is hard to > > > understand what you are trying to do > > > with this patch. > > > > > > > > > > > > > > > Signed-off-by: Shreeya Patel <shreeya.patel23498@xxxxxxxxx> > > > > --- > > > > drivers/staging/rtlwifi/base.c | 2 +- > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/staging/rtlwifi/base.c > > > > b/drivers/staging/rtlwifi/base.c > > > > index b88b0e8..5bb8f98 100644 > > > > --- a/drivers/staging/rtlwifi/base.c > > > > +++ b/drivers/staging/rtlwifi/base.c > > > > @@ -781,7 +781,7 @@ static void _rtl_txrate_selectmode(struct > > > > ieee80211_hw *hw, > > > > > > > > struct rtl_priv *rtlpriv = rtl_priv(hw); > > > > struct rtl_mac *mac = rtl_mac(rtl_priv(hw)); > > > > - struct rtl_sta_info *sta_entry = NULL; > > > > + struct rtl_sta_info *sta_entry; > > > Now the pointer just has garbage in it instead of the testable > > > value > > > of NULL. If you are concerned > > > with the dereference perhaps you could add a NULL check, again > > > it's > > > hard to say without seeing the > > > code. > > Hello, > > > > Thanks for making me understand. > > > > Here is the code after declaration and initialization of > > sta_entry. > > Will it be good to add a NULL check in this case? > > > > struct rtl_sta_info *sta_entry = NULL; > > u8 ratr_index = SET_RATE_ID(RATR_INX_WIRELESS_MC); > > > > if (sta) { > > sta_entry = (struct rtl_sta_info *)sta->drv_priv; > > ratr_index = sta_entry->ratr_index; > > } > Later in this function the macro SET_RATE_ID() is called, it relies > on sta_entry being NULL if it > was not explicitly set. > > Here is the macro; > > #define SET_RATE_ID(rate_id) \ > ((rtlpriv->cfg->spec_ver & RTL_SPEC_NEW_RATEID) ? \ > rtl_mrate_idx_to_arfr_id(hw, rate_id, \ > (sta_entry ? sta_entry->wireless_mode : > \ > WIRELESS_MODE_G)) : \ > rate_id) > > > > > If we are making a pointer point to NULL then what if any other > > variable is already pointing to NULL for some other purpose. > > Instead, removing initialization will be good right? > A pointer does not _point_ to NULL as such. A NULL pointer has a > value of all zero bytes. Have you > read (and completed all the exercises) in KnR > > https://en.wikipedia.org/wiki/The_C_Programming_Language > > It is, in my opinion, one of the best tech books ever written. If you > have any holes in your C > knowledge, this is the place to start. Thank you so much. I will make sure that I don't make the same mistake again. > > Good luck, > Tobin. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel