rcu: Remove SPARSE_RCU_POINTER Kconfig option

The sparse-based checking for non-RCU accesses to RCU-protected pointers
has been around for a very long time, and it is now the only type of
sparse-based checking that is optional.  This commit therefore makes
it unconditional.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>

diff --git a/Documentation/RCU/Design/Requirements/Requirements.html b/Documentation/RCU/Design/Requirements/Requirements.html
index 8c94fc1..0e6550a 100644 (file)
--- a/Documentation/RCU/Design/Requirements/Requirements.html
+++ b/Documentation/RCU/Design/Requirements/Requirements.html
@@ -559,9 +559,7 @@ The <tt>rcu_access_pointer()</tt> on line&nbsp;6 is similar to
        For <tt>remove_gp_synchronous()</tt>, as long as all modifications
        to <tt>gp</tt> are carried out while holding <tt>gp_lock</tt>,
        the above optimizations are harmless.
-       However,
-       with <tt>CONFIG_SPARSE_RCU_POINTER=y</tt>,
-       <tt>sparse</tt> will complain if you
+       However, <tt>sparse</tt> will complain if you
        define <tt>gp</tt> with <tt>__rcu</tt> and then
        access it without using
        either <tt>rcu_access_pointer()</tt> or <tt>rcu_dereference()</tt>.
@@ -1978,9 +1976,8 @@ guard against mishaps and misuse:
        and <tt>rcu_dereference()</tt>, perhaps (incorrectly)
        substituting a simple assignment.
        To catch this sort of error, a given RCU-protected pointer may be
-       tagged with <tt>__rcu</tt>, after which running sparse
-       with <tt>CONFIG_SPARSE_RCU_POINTER=y</tt> will complain
-       about simple-assignment accesses to that pointer.
+       tagged with <tt>__rcu</tt>, after which sparse
+       will complain about simple-assignment accesses to that pointer.
        Arnd Bergmann made me aware of this requirement, and also
        supplied the needed
        <a href="https://lwn.net/Articles/376011/">patch series</a>.

diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt
index 8779471..6beda55 100644 (file)
--- a/Documentation/RCU/checklist.txt
+++ b/Documentation/RCU/checklist.txt
@@ -413,11 +413,11 @@ over a rather long period of time, but improvements are always welcome!
        read-side critical sections.  It is the responsibility of the
        RCU update-side primitives to deal with this.
 
-17.    Use CONFIG_PROVE_RCU, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and the
-       __rcu sparse checks (enabled by CONFIG_SPARSE_RCU_POINTER) to
-       validate your RCU code.  These can help find problems as follows:
+17.    Use CONFIG_PROVE_LOCKING, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and the
+       __rcu sparse checks to validate your RCU code.  These can help
+       find problems as follows:
 
-       CONFIG_PROVE_RCU: check that accesses to RCU-protected data
+       CONFIG_PROVE_LOCKING: check that accesses to RCU-protected data
                structures are carried out under the proper RCU
                read-side critical section, while holding the right
                combination of locks, or whatever other conditions

diff --git a/Documentation/dev-tools/sparse.rst b/Documentation/dev-tools/sparse.rst
index ffdcc97..78aa00a 100644 (file)
--- a/Documentation/dev-tools/sparse.rst
+++ b/Documentation/dev-tools/sparse.rst
@@ -103,9 +103,3 @@ have already built it.
 
 The optional make variable CF can be used to pass arguments to sparse.  The
 build system passes -Wbitwise to sparse automatically.
-
-Checking RCU annotations
-~~~~~~~~~~~~~~~~~~~~~~~~
-
-RCU annotations are not checked by default.  To enable RCU annotation
-checks, include -DCONFIG_SPARSE_RCU_POINTER in your CF flags.

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index f811005..707242f 100644 (file)
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -17,11 +17,7 @@
 # define __release(x)  __context__(x,-1)
 # define __cond_lock(x,c)      ((c) ? ({ __acquire(x); 1; }) : 0)
 # define __percpu      __attribute__((noderef, address_space(3)))
-#ifdef CONFIG_SPARSE_RCU_POINTER
 # define __rcu         __attribute__((noderef, address_space(4)))
-#else /* CONFIG_SPARSE_RCU_POINTER */
-# define __rcu
-#endif /* CONFIG_SPARSE_RCU_POINTER */
 # define __private     __attribute__((noderef))
 extern void __chk_user_ptr(const volatile void __user *);
 extern void __chk_io_ptr(const volatile void __iomem *);

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 762deab..498d5dd 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1306,21 +1306,6 @@ menu "RCU Debugging"
 config PROVE_RCU
        def_bool PROVE_LOCKING
 
-config SPARSE_RCU_POINTER
-       bool "RCU debugging: sparse-based checks for pointer usage"
-       default n
-       help
-        This feature enables the __rcu sparse annotation for
-        RCU-protected pointers.  This annotation will cause sparse
-        to flag any non-RCU used of annotated pointers.  This can be
-        helpful when debugging RCU usage.  Please note that this feature
-        is not intended to enforce code cleanliness; it is instead merely
-        a debugging aid.
-
-        Say Y to make sparse flag questionable use of RCU-protected pointers
-
-        Say N if you are unsure.
-
 config TORTURE_TEST
        tristate
        default n

diff --git a/lib/Makefile b/lib/Makefile
index 0166fbc..07fbe6a 100644 (file)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -25,9 +25,6 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
         earlycpio.o seq_buf.o siphash.o \
         nmi_backtrace.o nodemask.o win_minmax.o
 
-CFLAGS_radix-tree.o += -DCONFIG_SPARSE_RCU_POINTER
-CFLAGS_idr.o += -DCONFIG_SPARSE_RCU_POINTER
-
 lib-$(CONFIG_MMU) += ioremap.o
 lib-$(CONFIG_SMP) += cpumask.o
 lib-$(CONFIG_DMA_NOOP_OPS) += dma-noop.o

diff --git a/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt b/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt
index b778a28..c5c29fb 100644 (file)
--- a/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt
+++ b/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt
@@ -74,10 +74,6 @@ CONFIG_TINY_RCU
 
        These are controlled by CONFIG_PREEMPT and/or CONFIG_SMP.
 
-CONFIG_SPARSE_RCU_POINTER
-
-       Makes sense only for sparse runs, not for kernel builds.
-
 CONFIG_SRCU
 CONFIG_TASKS_RCU