On Sat, May 25, 2024 at 09:32:29AM +0200, Nam Cao wrote: > This driver wants pxmitpriv->pxmitbuf to be 4-byte aligned. This is ensured > by allocating 4 more bytes than required with kmalloc(), then do the > p = p + 4 - (p & 3) trick to make sure the pointer is 4-byte aligned. > > This is unnecessary. Pointers from kmalloc() are already at least > 8-byte-aligned. > > Remove this alignment trick to simplify the code, and also to stop wasting > 4 extra bytes of dynamic memory allocator. > > This also gets rid of a (false) warning from kmemleak. This 4-byte-aligned > buffer is used to store pointers from kmalloc(). For 64-bit platforms, > pointer size is 8 bytes and kmemleak only scans for pointers in 8-byte > blocks, thus it misses the pointers stored in this 4-byte-aligned buffer > and thinks that these pointers have been leaked. This is just a false > warning, not a real problem. But still, it would be nice to get rid of > these warnings. Are you sure it's a false positive? I've always wondered what happens when you do: p = kmalloc(); kfree((char *)p + 4); regards, dan carpenter
