search for: ftrace_likely_upd

So as explained in Documentation/memory-barriers.txt e.g. a load followed by a store require a full memory barrier, to avoid store being ordered before the load. Similarly load-load requires a read memory barrier. Thinking about it, we can actually create a data dependency by mixing the first loaded value into the pointer being accessed. This adds an API for this and uses it in virtio. Written

...1); + return *(unsigned long *)addr; +} + +#endif /* __ASSEMBLY__ */ +#endif /* __ASM_GENERIC_RWONCE_H */ diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 204e76856435..718b4357af32 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -230,28 +230,6 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) #endif -/* - * Prevent the compiler from merging or refetching reads or writes. The - * compiler is also forbidden from reordering successive instances of - * READ_ONCE and WR...

...1); + return *(unsigned long *)addr; +} + +#endif /* __ASSEMBLY__ */ +#endif /* __ASM_GENERIC_RWONCE_H */ diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 204e76856435..718b4357af32 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -230,28 +230,6 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) #endif -/* - * Prevent the compiler from merging or refetching reads or writes. The - * compiler is also forbidden from reordering successive instances of - * READ_ONCE and WR...

...> + > +#endif > + > #ifdef CONFIG_SMP > > #ifndef smp_mb > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > index 6601d39e8c48..f599c30f1b28 100644 > --- a/include/linux/compiler.h > +++ b/include/linux/compiler.h > @@ -152,9 +152,13 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, > #endif > > #ifndef OPTIMIZER_HIDE_VAR > + > /* Make the optimizer believe the variable can be manipulated arbitrarily. */ > #define OPTIMIZER_HIDE_VAR(var) \ > __asm__ ("" : "=rm" (var) : "0...

...> + > +#endif > + > #ifdef CONFIG_SMP > > #ifndef smp_mb > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > index 6601d39e8c48..f599c30f1b28 100644 > --- a/include/linux/compiler.h > +++ b/include/linux/compiler.h > @@ -152,9 +152,13 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, > #endif > > #ifndef OPTIMIZER_HIDE_VAR > + > /* Make the optimizer believe the variable can be manipulated arbitrarily. */ > #define OPTIMIZER_HIDE_VAR(var) \ > __asm__ ("" : "=rm" (var) : "0...

...+ +#define dependent_ptr_mb(ptr, val) ({ mb(); (ptr); }) + +#endif + #ifdef CONFIG_SMP #ifndef smp_mb diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 6601d39e8c48..f599c30f1b28 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -152,9 +152,13 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, #endif #ifndef OPTIMIZER_HIDE_VAR + /* Make the optimizer believe the variable can be manipulated arbitrarily. */ #define OPTIMIZER_HIDE_VAR(var) \ __asm__ ("" : "=rm" (var) : "0" (var)) + +#define COMPILER_HAS_OPT...

...> > #ifdef CONFIG_SMP > > #ifndef smp_mb > > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > > index 6601d39e8c48..f599c30f1b28 100644 > > --- a/include/linux/compiler.h > > +++ b/include/linux/compiler.h > > @@ -152,9 +152,13 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, > > #endif > > #ifndef OPTIMIZER_HIDE_VAR > > + > > /* Make the optimizer believe the variable can be manipulated arbitrarily. */ > > #define OPTIMIZER_HIDE_VAR(var) \ > > __asm__ ("" : "=rm...

...c, sizeof(x)); \ + __u.__val; \ +}) + +#endif /* __ASSEMBLY__ */ +#endif /* __ASM_GENERIC_RWONCE_H */ diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 5e88e7e33abe..6de09d2f42ad 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -177,118 +177,6 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) #endif -#include <uapi/linux/types.h> - -#define __READ_ONCE_SIZE \ -({ \ - switch (size) { \ - case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \...

...+#endif /* CONFIG_GENERIC_BUG */ /* * Don't use BUG() or BUG_ON() unless there's really no way out; one diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 06396c1..fc5004a 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -99,13 +99,22 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, * unique, to convince GCC not to merge duplicate inline asm statements. */ #define annotate_reachable() ({ \ - asm volatile("ANNOTATE_REACHABLE counter=%c0" \ - : : "i" (__COUNTER__)); \ + asm volatile("%c0:\n\t...

...+#endif /* CONFIG_GENERIC_BUG */ /* * Don't use BUG() or BUG_ON() unless there's really no way out; one diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 06396c1..fc5004a 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -99,13 +99,22 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, * unique, to convince GCC not to merge duplicate inline asm statements. */ #define annotate_reachable() ({ \ - asm volatile("ANNOTATE_REACHABLE counter=%c0" \ - : : "i" (__COUNTER__)); \ + asm volatile("%c0:\n\t...

...+#endif /* CONFIG_GENERIC_BUG */ /* * Don't use BUG() or BUG_ON() unless there's really no way out; one diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 06396c1..fc5004a 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -99,13 +99,22 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, * unique, to convince GCC not to merge duplicate inline asm statements. */ #define annotate_reachable() ({ \ - asm volatile("ANNOTATE_REACHABLE counter=%c0" \ - : : "i" (__COUNTER__)); \ + asm volatile("%c0:\n\t...

Hi all, This is version three of the patches I previously posted here: v1: https://lore.kernel.org/lkml/20191108170120.22331-1-will at kernel.org/ v2: https://lore.kernel.org/r/20200630173734.14057-1-will at kernel.org Changes since v2 include: * Actually add the barrier in READ_ONCE() for Alpha! * Implement Alpha's smp_load_acquire() using __READ_ONCE(), rather than the other

Hi everyone, This is the long-awaited version two of the patches I previously posted in November last year: https://lore.kernel.org/lkml/20191108170120.22331-1-will at kernel.org/ I ended up parking the series while the READ_ONCE() implementation was being overhauled, but with that merged during the recent merge window and LTO patches being posted again [1], it was time for a refresh. The

Hi everyone, This is the long-awaited version two of the patches I previously posted in November last year: https://lore.kernel.org/lkml/20191108170120.22331-1-will at kernel.org/ I ended up parking the series while the READ_ONCE() implementation was being overhauled, but with that merged during the recent merge window and LTO patches being posted again [1], it was time for a refresh. The

Hi all, Although [smp_]read_barrier_depends() became part of READ_ONCE() in commit 76ebbe78f739 ("locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE()"), it still limps on in the Linux memory model with the sinister hope of attracting innocent new users so that it becomes impossible to remove altogether. Let's strike before it's too late: there's only