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srcu: Create CPP macros for normal and NMI-safe SRCU readers

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This commit creates SRCU_READ_FLAVOR_NORMAL and SRCU_READ_FLAVOR_NMI
C-preprocessor macros for srcu_read_lock() and srcu_read_lock_nmisafe(),
respectively.  These replace the old true/false values that were
previously passed to srcu_check_read_flavor().  In addition, the
srcu_check_read_flavor() function itself requires a bit of rework to
handle bitmasks instead of true/false values.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: <bpf@vger.kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
This commit is contained in:
Paul E. McKenney 2024-10-15 09:11:04 -07:00 committed by Frederic Weisbecker
parent c071b8e535
commit 05829be27f
3 changed files with 23 additions and 22 deletions
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20
include/linux/srcu.h
View File

@ -176,10 +176,6 @@ static inline int srcu_read_lock_held(const struct srcu_struct *ssp)
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
#define SRCU_NMI_UNKNOWN 0x0
#define SRCU_NMI_UNSAFE 0x1
#define SRCU_NMI_SAFE 0x2
#if defined(CONFIG_PROVE_RCU) && defined(CONFIG_TREE_SRCU)
void srcu_check_read_flavor(struct srcu_struct *ssp, int read_flavor);
#else
@ -247,7 +243,7 @@ static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp)
{
int retval;
srcu_check_read_flavor(ssp, false);
srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
retval = __srcu_read_lock(ssp);
srcu_lock_acquire(&ssp->dep_map);
return retval;
@ -268,7 +264,7 @@ static inline int srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp
{
int retval;
srcu_check_read_flavor(ssp, true);
srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NMI);
retval = __srcu_read_lock_nmisafe(ssp);
rcu_try_lock_acquire(&ssp->dep_map);
return retval;
@ -280,7 +276,7 @@ srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp)
{
int retval;
srcu_check_read_flavor(ssp, false);
srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
retval = __srcu_read_lock(ssp);
return retval;
}
@ -309,7 +305,7 @@ srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp)
static inline int srcu_down_read(struct srcu_struct *ssp) __acquires(ssp)
{
WARN_ON_ONCE(in_nmi());
srcu_check_read_flavor(ssp, false);
srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
return __srcu_read_lock(ssp);
}
@ -324,7 +320,7 @@ static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx)
__releases(ssp)
{
WARN_ON_ONCE(idx & ~0x1);
srcu_check_read_flavor(ssp, false);
srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
srcu_lock_release(&ssp->dep_map);
__srcu_read_unlock(ssp, idx);
}
@ -340,7 +336,7 @@ static inline void srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx)
__releases(ssp)
{
WARN_ON_ONCE(idx & ~0x1);
srcu_check_read_flavor(ssp, true);
srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NMI);
rcu_lock_release(&ssp->dep_map);
__srcu_read_unlock_nmisafe(ssp, idx);
}
@ -349,7 +345,7 @@ static inline void srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx)
static inline notrace void
srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp)
{
srcu_check_read_flavor(ssp, false);
srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
__srcu_read_unlock(ssp, idx);
}
@ -366,7 +362,7 @@ static inline void srcu_up_read(struct srcu_struct *ssp, int idx)
{
WARN_ON_ONCE(idx & ~0x1);
WARN_ON_ONCE(in_nmi());
srcu_check_read_flavor(ssp, false);
srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL);
__srcu_read_unlock(ssp, idx);
}

4
include/linux/srcutree.h
View File

@ -43,6 +43,10 @@ struct srcu_data {
struct srcu_struct *ssp;
};
/* Values for ->srcu_reader_flavor. */
#define SRCU_READ_FLAVOR_NORMAL 0x1 // srcu_read_lock().
#define SRCU_READ_FLAVOR_NMI 0x2 // srcu_read_lock_nmisafe().
/*
* Node in SRCU combining tree, similar in function to rcu_data.
*/

21
kernel/rcu/srcutree.c
View File

@ -463,7 +463,7 @@ static unsigned long srcu_readers_unlock_idx(struct srcu_struct *ssp, int idx)
mask = mask | READ_ONCE(sdp->srcu_reader_flavor);
}
WARN_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && (mask & (mask - 1)),
"Mixed NMI-safe readers for srcu_struct at %ps.\n", ssp);
"Mixed reader flavors for srcu_struct at %ps.\n", ssp);
return sum;
}
@ -703,20 +703,21 @@ EXPORT_SYMBOL_GPL(cleanup_srcu_struct);
*/
void srcu_check_read_flavor(struct srcu_struct *ssp, int read_flavor)
{
int reader_flavor_mask = 1 << read_flavor;
int old_reader_flavor_mask;
int old_read_flavor;
struct srcu_data *sdp;
/* NMI-unsafe use in NMI is a bad sign */
WARN_ON_ONCE(!read_flavor && in_nmi());
/* NMI-unsafe use in NMI is a bad sign, as is multi-bit read_flavor values. */
WARN_ON_ONCE((read_flavor != SRCU_READ_FLAVOR_NMI) && in_nmi());
WARN_ON_ONCE(read_flavor & (read_flavor - 1));
sdp = raw_cpu_ptr(ssp->sda);
old_reader_flavor_mask = READ_ONCE(sdp->srcu_reader_flavor);
if (!old_reader_flavor_mask) {
old_reader_flavor_mask = cmpxchg(&sdp->srcu_reader_flavor, 0, reader_flavor_mask);
if (!old_reader_flavor_mask)
old_read_flavor = READ_ONCE(sdp->srcu_reader_flavor);
if (!old_read_flavor) {
old_read_flavor = cmpxchg(&sdp->srcu_reader_flavor, 0, read_flavor);
if (!old_read_flavor)
return;
}
WARN_ONCE(old_reader_flavor_mask != reader_flavor_mask, "CPU %d old state %d new state %d\n", sdp->cpu, old_reader_flavor_mask, reader_flavor_mask);
WARN_ONCE(old_read_flavor != read_flavor, "CPU %d old state %d new state %d\n", sdp->cpu, old_read_flavor, read_flavor);
}
EXPORT_SYMBOL_GPL(srcu_check_read_flavor);
#endif /* CONFIG_PROVE_RCU */