linux-toradex.git/include/linux/rcupdate.h, branch v5.10-rc3

treewide: Convert macro and uses of section(foo) to section("foo")

2020-10-25T21:51:49+00:00

Use a more generic form for __section that requires quotes to avoid
complications with clang and gcc differences.

Remove the quote operator # from compiler_attributes.h __section macro.

Convert all unquoted __section(foo) uses to quoted __section("foo").
Also convert __attribute__((section("foo"))) uses to __section("foo")
even if the __attribute__ has multiple list entry forms.

Conversion done using the script at:

    https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl

Signed-off-by: Joe Perches 
Reviewed-by: Nick Desaulniers 
Reviewed-by: Miguel Ojeda 
Signed-off-by: Linus Torvalds

Merge branch 'strictgp.2020.08.24a' into HEAD

2020-09-03T16:47:42+00:00

strictgp.2020.08.24a: Strict grace periods for KASAN testing.

rcu: Report QS for outermost PREEMPT=n rcu_read_unlock() for strict GPs

2020-08-25T01:40:28+00:00

The CONFIG_PREEMPT=n instance of rcu_read_unlock is even more
aggressively than that of CONFIG_PREEMPT=y in deferring reporting
quiescent states to the RCU core.  This is just what is wanted in normal
use because it reduces overhead, but the resulting delay is not what
is wanted for kernels built with CONFIG_RCU_STRICT_GRACE_PERIOD=y.
This commit therefore adds an rcu_read_unlock_strict() function that
checks for exceptional conditions, and reports the newly started
quiescent state if it is safe to do so, also doing a spin-delay if
requested via rcutree.rcu_unlock_delay.  This commit also adds a call
to rcu_read_unlock_strict() from the CONFIG_PREEMPT=n instance of
__rcu_read_unlock().

[ paulmck: Fixed bug located by kernel test robot  ]
Reported-by Jann Horn 
Signed-off-by: Paul E. McKenney

rcu: Fix kerneldoc comments in rcupdate.h

2020-08-25T01:36:08+00:00

This commit fixes the kerneldoc comments for rcu_read_unlock_bh(),
rcu_read_unlock_sched() and rcu_head_after_call_rcu() so they e.g. get
properly linked in the API documentation. Also add parenthesis after
function names to match the notation used in other kerneldoc comments in
the same file.

Signed-off-by: Tobias Klauser 
Signed-off-by: Paul E. McKenney

rcu: Introduce single argument kvfree_rcu() interface

2020-06-29T18:59:26+00:00

Make kvfree_rcu() capable of freeing objects that will not
embed an rcu_head within it. This saves storage overhead in
such objects. Reclaiming headless objects this way requires
only a single argument (pointer to the object).

After this patch, there are two ways to use kvfree_rcu():

a) kvfree_rcu(ptr, rhf);
    struct X {
        struct rcu_head rhf;
        unsigned char data[100];
    };

    void *ptr = kvmalloc(sizeof(struct X), GFP_KERNEL);
    if (ptr)
        kvfree_rcu(ptr, rhf);

b) kvfree_rcu(ptr);
    void *ptr = kvmalloc(some_bytes, GFP_KERNEL);
    if (ptr)
        kvfree_rcu(ptr);

Note that the headless usage (example b) can only be used in a code
that can sleep. This is enforced by the CONFIG_DEBUG_ATOMIC_SLEEP
option.

Co-developed-by: Joel Fernandes (Google) 
Reviewed-by: Joel Fernandes (Google) 
Signed-off-by: Uladzislau Rezki (Sony) 
Signed-off-by: Paul E. McKenney

rcu: Introduce 2 arg kvfree_rcu() interface

2020-06-29T18:59:25+00:00

kvmalloc() can allocate two types of objects: SLAB backed
and vmalloc backed. How it behaves depends on requested
object's size and memory pressure.

Add a kvfree_rcu() interface that can free memory allocated
via kvmalloc(). It is a simple alias to kfree_rcu() which
can now handle either type of object.


    struct test_kvfree_rcu {
        struct rcu_head rcu;
        unsigned char array[100];
    };

    struct test_kvfree_rcu *p;

    p = kvmalloc(10 * PAGE_SIZE);
    if (p)
        kvfree_rcu(p, rcu);


Signed-off-by: Uladzislau Rezki (Sony) 
Co-developed-by: Joel Fernandes (Google) 
Reviewed-by: Joel Fernandes (Google) 
Signed-off-by: Joel Fernandes (Google) 
Signed-off-by: Paul E. McKenney

rcu: Rename _kfree_callback/_kfree_rcu_offset/kfree_call_*

2020-06-29T18:59:25+00:00

The following changes are introduced:

1. Rename rcu_invoke_kfree_callback() to rcu_invoke_kvfree_callback(),
as well as the associated trace events, so the rcu_kfree_callback(),
becomes rcu_kvfree_callback(). The reason is to be aligned with kvfree()
notation.

2. Rename __is_kfree_rcu_offset to __is_kvfree_rcu_offset. All RCU
paths use kvfree() now instead of kfree(), thus rename it.

3. Rename kfree_call_rcu() to the kvfree_call_rcu(). The reason is,
it is capable of freeing vmalloc() memory now. Do the same with
__kfree_rcu() macro, it becomes __kvfree_rcu(), the goal is the
same.

Reviewed-by: Joel Fernandes (Google) 
Co-developed-by: Joel Fernandes (Google) 
Signed-off-by: Joel Fernandes (Google) 
Signed-off-by: Uladzislau Rezki (Sony) 
Signed-off-by: Paul E. McKenney

rcu-tasks: Make RCU Tasks Trace make use of RCU scheduler hooks

2020-04-27T18:03:52+00:00

This commit makes the calls to rcu_tasks_qs() detect and report
quiescent states for RCU tasks trace.  If the task is in a quiescent
state and if ->trc_reader_checked is not yet set, the task sets its own
->trc_reader_checked.  This will cause the grace-period kthread to
remove it from the holdout list if it still remains there.

[ paulmck: Fix conditional compilation per kbuild test robot feedback. ]
Signed-off-by: Paul E. McKenney

rcu-tasks: Add an RCU-tasks rude variant

2020-04-27T18:03:51+00:00

This commit adds a "rude" variant of RCU-tasks that has as quiescent
states schedule(), cond_resched_tasks_rcu_qs(), userspace execution,
and (in theory, anyway) cond_resched().  In other words, RCU-tasks rude
readers are regions of code with preemption disabled, but excluding code
early in the CPU-online sequence and late in the CPU-offline sequence.
Updates make use of IPIs and force an IPI and a context switch on each
online CPU.  This variant is useful in some situations in tracing.

Suggested-by: Steven Rostedt 
[ paulmck: Apply EXPORT_SYMBOL_GPL() feedback from Qiujun Huang. ]
Signed-off-by: Paul E. McKenney 
[ paulmck: Apply review feedback from Steve Rostedt. ]

rcu-tasks: Refactor RCU-tasks to allow variants to be added