Messages in this thread | | | Date | Wed, 09 Aug 2023 16:44:24 +0200 | From | Takashi Iwai <> | Subject | Re: [PATCH RFC] Introduce uniptr_t as a generic "universal" pointer |
| |
On Wed, 09 Aug 2023 16:38:01 +0200, Christoph Hellwig wrote: > > On Wed, Aug 09, 2023 at 04:35:47PM +0200, Takashi Iwai wrote: > > Although sockptr_t is used already in several places as a "universal" > > pointer, it's still too confusing to use it in other subsystems, since > > people see it always as if it were a network-related stuff. > > > > This patch defines a more generic type, uniptr_t, that does exactly as > > same as sockptr_t for a wider use. As of now, it's almost 1:1 copy > > with renames (just with comprehensive header file inclusions). > > The original set_fs removal series did that as uptr_t, and Linus > hated it with passion. I somehow doubt he's going to like it more now.
Ah, good to know!
The remaining question is whether the use of sockptr_t for other subsystems as a generic pointer is a recommended / acceptable move...
Takashi
> > Signed-off-by: Takashi Iwai <tiwai@suse.de> > > --- > > > > This is a RFC patch, or rather a material for bikeshedding. > > > > Initially the discussion started from the use of sockptr_t for the > > sound driver in Andy's patch: > > https://lore.kernel.org/r/20230721100146.67293-1-andriy.shevchenko@linux.intel.com > > followed by a bigger series of patches by me: > > https://lore.kernel.org/r/20230731154718.31048-1-tiwai@suse.de > > > > The first reaction to the patches (including my own) were > > "why sockptr_t?" Yes, it's just confusing. So, here it is, a > > proposal of defining the new type for the very purpose as sockptr_t. > > > > The name of uniptr_t is nothing but my random pick up, and we can > > endlessly discuss for a better name (genptr_t or whatever). > > I'm totally open for the name. > > > > After this introduction, sockptr_t can be alias of uniptr_t, > > e.g. simply override with "#define sockptr_t uniptr_t" or such. > > How can it be is another open question. > > > > Also, we can clean up the macro implementation along with it; > > there seem a few (rather minor) issues as suggested by Andy: > > https://lore.kernel.org/r/ZMlGKy7ibjkQ6ii7@smile.fi.intel.com > > > > Honestly speaking, I don't mind to keep using sockptr_t generically > > despite of the name, if people agree. The rename might make sense, > > though, if it's more widely used in other subsystems in future. > > > > > > Takashi > > > > === > > > > include/linux/uniptr.h | 121 +++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 121 insertions(+) > > create mode 100644 include/linux/uniptr.h > > > > diff --git a/include/linux/uniptr.h b/include/linux/uniptr.h > > new file mode 100644 > > index 000000000000..f7994d3a45eb > > --- /dev/null > > +++ b/include/linux/uniptr.h > > @@ -0,0 +1,121 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > +/* > > + * Support for "universal" pointers that can point to either kernel or userspace > > + * memory. > > + * > > + * Original code from sockptr.h > > + * Copyright (c) 2020 Christoph Hellwig > > + */ > > +#ifndef _LINUX_UNIPTR_H > > +#define _LINUX_UNIPTR_H > > + > > +#include <linux/err.h> > > +#include <linux/slab.h> > > +#include <linux/string.h> > > +#include <linux/types.h> > > +#include <linux/uaccess.h> > > + > > +typedef struct { > > + union { > > + void *kernel; > > + void __user *user; > > + }; > > + bool is_kernel : 1; > > +} uniptr_t; > > + > > +static inline bool uniptr_is_kernel(uniptr_t uniptr) > > +{ > > + return uniptr.is_kernel; > > +} > > + > > +static inline uniptr_t KERNEL_UNIPTR(void *p) > > +{ > > + return (uniptr_t) { .kernel = p, .is_kernel = true }; > > +} > > + > > +static inline uniptr_t USER_UNIPTR(void __user *p) > > +{ > > + return (uniptr_t) { .user = p }; > > +} > > + > > +static inline bool uniptr_is_null(uniptr_t uniptr) > > +{ > > + if (uniptr_is_kernel(uniptr)) > > + return !uniptr.kernel; > > + return !uniptr.user; > > +} > > + > > +static inline int copy_from_uniptr_offset(void *dst, uniptr_t src, > > + size_t offset, size_t size) > > +{ > > + if (!uniptr_is_kernel(src)) > > + return copy_from_user(dst, src.user + offset, size); > > + memcpy(dst, src.kernel + offset, size); > > + return 0; > > +} > > + > > +static inline int copy_from_uniptr(void *dst, uniptr_t src, size_t size) > > +{ > > + return copy_from_uniptr_offset(dst, src, 0, size); > > +} > > + > > +static inline int copy_to_uniptr_offset(uniptr_t dst, size_t offset, > > + const void *src, size_t size) > > +{ > > + if (!uniptr_is_kernel(dst)) > > + return copy_to_user(dst.user + offset, src, size); > > + memcpy(dst.kernel + offset, src, size); > > + return 0; > > +} > > + > > +static inline int copy_to_uniptr(uniptr_t dst, const void *src, size_t size) > > +{ > > + return copy_to_uniptr_offset(dst, 0, src, size); > > +} > > + > > +static inline void *memdup_uniptr(uniptr_t src, size_t len) > > +{ > > + void *p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN); > > + > > + if (!p) > > + return ERR_PTR(-ENOMEM); > > + if (copy_from_uniptr(p, src, len)) { > > + kfree(p); > > + return ERR_PTR(-EFAULT); > > + } > > + return p; > > +} > > + > > +static inline void *memdup_uniptr_nul(uniptr_t src, size_t len) > > +{ > > + char *p = kmalloc_track_caller(len + 1, GFP_KERNEL); > > + > > + if (!p) > > + return ERR_PTR(-ENOMEM); > > + if (copy_from_uniptr(p, src, len)) { > > + kfree(p); > > + return ERR_PTR(-EFAULT); > > + } > > + p[len] = '\0'; > > + return p; > > +} > > + > > +static inline long strncpy_from_uniptr(char *dst, uniptr_t src, size_t count) > > +{ > > + if (uniptr_is_kernel(src)) { > > + size_t len = min(strnlen(src.kernel, count - 1) + 1, count); > > + > > + memcpy(dst, src.kernel, len); > > + return len; > > + } > > + return strncpy_from_user(dst, src.user, count); > > +} > > + > > +static inline int check_zeroed_uniptr(uniptr_t src, size_t offset, size_t size) > > +{ > > + if (!uniptr_is_kernel(src)) > > + return check_zeroed_user(src.user + offset, size); > > + return memchr_inv(src.kernel + offset, 0, size) == NULL; > > +} > > + > > +#endif /* _LINUX_UNIPTR_H */ > > -- > > 2.35.3 > ---end quoted text--- >
| |