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Merge branches 'doc.2021.01.06a', 'fixes.2021.01.04b', 'kfree_rcu.2021.01.04a', 'mmdumpobj.2021.01.22a', 'nocb.2021.01.06a', 'rt.2021.01.04a', 'stall.2021.01.06a', 'torture.2021.01.12a' and 'tortureall.2021.01.06a' into HEAD

Browse source 
doc.2021.01.06a: Documentation updates.
fixes.2021.01.04b: Miscellaneous fixes.
kfree_rcu.2021.01.04a: kfree_rcu() updates.
mmdumpobj.2021.01.22a: Dump allocation point for memory blocks.
nocb.2021.01.06a: RCU callback offload updates and cblist segment lengths.
rt.2021.01.04a: Real-time updates.
stall.2021.01.06a: RCU CPU stall warning updates.
torture.2021.01.12a: Torture-test updates and polling SRCU grace-period API.
tortureall.2021.01.06a: Torture-test script updates.
This commit is contained in:
Paul E. McKenney 2021-01-22 15:26:44 -08:00
commit 0d2460ba61
57 changed files with 2651 additions and 349 deletions
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147
kernel/rcu/srcutree.c
View file

@ -807,6 +807,46 @@ static void srcu_leak_callback(struct rcu_head *rhp)
{
}
/*
* Start an SRCU grace period, and also queue the callback if non-NULL.
*/
static unsigned long srcu_gp_start_if_needed(struct srcu_struct *ssp,
struct rcu_head *rhp, bool do_norm)
{
unsigned long flags;
int idx;
bool needexp = false;
bool needgp = false;
unsigned long s;
struct srcu_data *sdp;
check_init_srcu_struct(ssp);
idx = srcu_read_lock(ssp);
sdp = raw_cpu_ptr(ssp->sda);
spin_lock_irqsave_rcu_node(sdp, flags);
if (rhp)
rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp);
rcu_segcblist_advance(&sdp->srcu_cblist,
rcu_seq_current(&ssp->srcu_gp_seq));
s = rcu_seq_snap(&ssp->srcu_gp_seq);
(void)rcu_segcblist_accelerate(&sdp->srcu_cblist, s);
if (ULONG_CMP_LT(sdp->srcu_gp_seq_needed, s)) {
sdp->srcu_gp_seq_needed = s;
needgp = true;
}
if (!do_norm && ULONG_CMP_LT(sdp->srcu_gp_seq_needed_exp, s)) {
sdp->srcu_gp_seq_needed_exp = s;
needexp = true;
}
spin_unlock_irqrestore_rcu_node(sdp, flags);
if (needgp)
srcu_funnel_gp_start(ssp, sdp, s, do_norm);
else if (needexp)
srcu_funnel_exp_start(ssp, sdp->mynode, s);
srcu_read_unlock(ssp, idx);
return s;
}
/*
* Enqueue an SRCU callback on the srcu_data structure associated with
* the current CPU and the specified srcu_struct structure, initiating
@ -838,14 +878,6 @@ static void srcu_leak_callback(struct rcu_head *rhp)
static void __call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp,
rcu_callback_t func, bool do_norm)
{
unsigned long flags;
int idx;
bool needexp = false;
bool needgp = false;
unsigned long s;
struct srcu_data *sdp;
check_init_srcu_struct(ssp);
if (debug_rcu_head_queue(rhp)) {
/* Probable double call_srcu(), so leak the callback. */
WRITE_ONCE(rhp->func, srcu_leak_callback);
@ -853,28 +885,7 @@ static void __call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp,
return;
}
rhp->func = func;
idx = srcu_read_lock(ssp);
sdp = raw_cpu_ptr(ssp->sda);
spin_lock_irqsave_rcu_node(sdp, flags);
rcu_segcblist_enqueue(&sdp->srcu_cblist, rhp);
rcu_segcblist_advance(&sdp->srcu_cblist,
rcu_seq_current(&ssp->srcu_gp_seq));
s = rcu_seq_snap(&ssp->srcu_gp_seq);
(void)rcu_segcblist_accelerate(&sdp->srcu_cblist, s);
if (ULONG_CMP_LT(sdp->srcu_gp_seq_needed, s)) {
sdp->srcu_gp_seq_needed = s;
needgp = true;
}
if (!do_norm && ULONG_CMP_LT(sdp->srcu_gp_seq_needed_exp, s)) {
sdp->srcu_gp_seq_needed_exp = s;
needexp = true;
}
spin_unlock_irqrestore_rcu_node(sdp, flags);
if (needgp)
srcu_funnel_gp_start(ssp, sdp, s, do_norm);
else if (needexp)
srcu_funnel_exp_start(ssp, sdp->mynode, s);
srcu_read_unlock(ssp, idx);
(void)srcu_gp_start_if_needed(ssp, rhp, do_norm);
}
/**
@ -1003,6 +1014,77 @@ void synchronize_srcu(struct srcu_struct *ssp)
}
EXPORT_SYMBOL_GPL(synchronize_srcu);
/**
* get_state_synchronize_srcu - Provide an end-of-grace-period cookie
* @ssp: srcu_struct to provide cookie for.
*
* This function returns a cookie that can be passed to
* poll_state_synchronize_srcu(), which will return true if a full grace
* period has elapsed in the meantime. It is the caller's responsibility
* to make sure that grace period happens, for example, by invoking
* call_srcu() after return from get_state_synchronize_srcu().
*/
unsigned long get_state_synchronize_srcu(struct srcu_struct *ssp)
{
// Any prior manipulation of SRCU-protected data must happen
// before the load from ->srcu_gp_seq.
smp_mb();
return rcu_seq_snap(&ssp->srcu_gp_seq);
}
EXPORT_SYMBOL_GPL(get_state_synchronize_srcu);
/**
* start_poll_synchronize_srcu - Provide cookie and start grace period
* @ssp: srcu_struct to provide cookie for.
*
* This function returns a cookie that can be passed to
* poll_state_synchronize_srcu(), which will return true if a full grace
* period has elapsed in the meantime. Unlike get_state_synchronize_srcu(),
* this function also ensures that any needed SRCU grace period will be
* started. This convenience does come at a cost in terms of CPU overhead.
*/
unsigned long start_poll_synchronize_srcu(struct srcu_struct *ssp)
{
return srcu_gp_start_if_needed(ssp, NULL, true);
}
EXPORT_SYMBOL_GPL(start_poll_synchronize_srcu);
/**
* poll_state_synchronize_srcu - Has cookie's grace period ended?
* @ssp: srcu_struct to provide cookie for.
* @cookie: Return value from get_state_synchronize_srcu() or start_poll_synchronize_srcu().
*
* This function takes the cookie that was returned from either
* get_state_synchronize_srcu() or start_poll_synchronize_srcu(), and
* returns @true if an SRCU grace period elapsed since the time that the
* cookie was created.
*
* Because cookies are finite in size, wrapping/overflow is possible.
* This is more pronounced on 32-bit systems where cookies are 32 bits,
* where in theory wrapping could happen in about 14 hours assuming
* 25-microsecond expedited SRCU grace periods. However, a more likely
* overflow lower bound is on the order of 24 days in the case of
* one-millisecond SRCU grace periods. Of course, wrapping in a 64-bit
* system requires geologic timespans, as in more than seven million years
* even for expedited SRCU grace periods.
*
* Wrapping/overflow is much more of an issue for CONFIG_SMP=n systems
* that also have CONFIG_PREEMPTION=n, which selects Tiny SRCU. This uses
* a 16-bit cookie, which rcutorture routinely wraps in a matter of a
* few minutes. If this proves to be a problem, this counter will be
* expanded to the same size as for Tree SRCU.
*/
bool poll_state_synchronize_srcu(struct srcu_struct *ssp, unsigned long cookie)
{
if (!rcu_seq_done(&ssp->srcu_gp_seq, cookie))
return false;
// Ensure that the end of the SRCU grace period happens before
// any subsequent code that the caller might execute.
smp_mb(); // ^^^
return true;
}
EXPORT_SYMBOL_GPL(poll_state_synchronize_srcu);
/*
* Callback function for srcu_barrier() use.
*/
@ -1160,6 +1242,7 @@ static void srcu_advance_state(struct srcu_struct *ssp)
*/
static void srcu_invoke_callbacks(struct work_struct *work)
{
long len;
bool more;
struct rcu_cblist ready_cbs;
struct rcu_head *rhp;
@ -1182,6 +1265,7 @@ static void srcu_invoke_callbacks(struct work_struct *work)
/* We are on the job! Extract and invoke ready callbacks. */
sdp->srcu_cblist_invoking = true;
rcu_segcblist_extract_done_cbs(&sdp->srcu_cblist, &ready_cbs);
len = ready_cbs.len;
spin_unlock_irq_rcu_node(sdp);
rhp = rcu_cblist_dequeue(&ready_cbs);
for (; rhp != NULL; rhp = rcu_cblist_dequeue(&ready_cbs)) {
@ -1190,13 +1274,14 @@ static void srcu_invoke_callbacks(struct work_struct *work)
rhp->func(rhp);
local_bh_enable();
}
WARN_ON_ONCE(ready_cbs.len);
/*
* Update counts, accelerate new callbacks, and if needed,
* schedule another round of callback invocation.
*/
spin_lock_irq_rcu_node(sdp);
rcu_segcblist_insert_count(&sdp->srcu_cblist, &ready_cbs);
rcu_segcblist_add_len(&sdp->srcu_cblist, -len);
(void)rcu_segcblist_accelerate(&sdp->srcu_cblist,
rcu_seq_snap(&ssp->srcu_gp_seq));
sdp->srcu_cblist_invoking = false;