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Revert "rcu-tasks: Fix access non-existent percpu rtpcp variable in rcu_tasks_need_gpcb()"

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This reverts commit 224fd631c4 which is
commit fd70e9f1d8 upstream.

It is reported to cause problems in testing, so revert it for now.

Link: https://lore.kernel.org/r/20241216-comic-handling-3bcf108cc465@wendy
Reported-by: Conor Dooley <conor.dooley@microchip.com>
CC: Zhixu Liu <zhixu.liu@gmail.com>
Cc: Zqiang <qiang.zhang1211@gmail.com>
Cc: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Xiangyu Chen <xiangyu.chen@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2024-12-30 15:47:08 +01:00
parent 36775f42e0
commit acddb87620
1 changed files with 28 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

82
kernel/rcu/tasks.h
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@ -31,7 +31,6 @@ typedef void (*postgp_func_t)(struct rcu_tasks *rtp);
* @barrier_q_head: RCU callback for barrier operation.
* @rtp_blkd_tasks: List of tasks blocked as readers.
* @cpu: CPU number corresponding to this entry.
* @index: Index of this CPU in rtpcp_array of the rcu_tasks structure.
* @rtpp: Pointer to the rcu_tasks structure.
*/
struct rcu_tasks_percpu {
@ -44,7 +43,6 @@ struct rcu_tasks_percpu {
struct rcu_head barrier_q_head;
struct list_head rtp_blkd_tasks;
int cpu;
int index;
struct rcu_tasks *rtpp;
};
@ -70,7 +68,6 @@ struct rcu_tasks_percpu {
* @postgp_func: This flavor's post-grace-period function (optional).
* @call_func: This flavor's call_rcu()-equivalent function.
* @rtpcpu: This flavor's rcu_tasks_percpu structure.
* @rtpcp_array: Array of pointers to rcu_tasks_percpu structure of CPUs in cpu_possible_mask.
* @percpu_enqueue_shift: Shift down CPU ID this much when enqueuing callbacks.
* @percpu_enqueue_lim: Number of per-CPU callback queues in use for enqueuing.
* @percpu_dequeue_lim: Number of per-CPU callback queues in use for dequeuing.
@ -103,7 +100,6 @@ struct rcu_tasks {
postgp_func_t postgp_func;
call_rcu_func_t call_func;
struct rcu_tasks_percpu __percpu *rtpcpu;
struct rcu_tasks_percpu **rtpcp_array;
int percpu_enqueue_shift;
int percpu_enqueue_lim;
int percpu_dequeue_lim;
@ -168,8 +164,6 @@ module_param(rcu_task_contend_lim, int, 0444);
static int rcu_task_collapse_lim __read_mostly = 10;
module_param(rcu_task_collapse_lim, int, 0444);
static int rcu_task_cpu_ids;
/* RCU tasks grace-period state for debugging. */
#define RTGS_INIT 0
#define RTGS_WAIT_WAIT_CBS 1
@ -234,8 +228,6 @@ static void cblist_init_generic(struct rcu_tasks *rtp)
unsigned long flags;
int lim;
int shift;
int maxcpu;
int index = 0;
raw_spin_lock_irqsave(&rtp->cbs_gbl_lock, flags);
if (rcu_task_enqueue_lim < 0) {
@ -246,9 +238,14 @@ static void cblist_init_generic(struct rcu_tasks *rtp)
}
lim = rcu_task_enqueue_lim;
rtp->rtpcp_array = kcalloc(num_possible_cpus(), sizeof(struct rcu_tasks_percpu *), GFP_KERNEL);
BUG_ON(!rtp->rtpcp_array);
if (lim > nr_cpu_ids)
lim = nr_cpu_ids;
shift = ilog2(nr_cpu_ids / lim);
if (((nr_cpu_ids - 1) >> shift) >= lim)
shift++;
WRITE_ONCE(rtp->percpu_enqueue_shift, shift);
WRITE_ONCE(rtp->percpu_dequeue_lim, lim);
smp_store_release(&rtp->percpu_enqueue_lim, lim);
for_each_possible_cpu(cpu) {
struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu);
@ -261,33 +258,16 @@ static void cblist_init_generic(struct rcu_tasks *rtp)
INIT_WORK(&rtpcp->rtp_work, rcu_tasks_invoke_cbs_wq);
rtpcp->cpu = cpu;
rtpcp->rtpp = rtp;
rtpcp->index = index;
rtp->rtpcp_array[index] = rtpcp;
index++;
if (!rtpcp->rtp_blkd_tasks.next)
INIT_LIST_HEAD(&rtpcp->rtp_blkd_tasks);
raw_spin_unlock_rcu_node(rtpcp); // irqs remain disabled.
maxcpu = cpu;
}
raw_spin_unlock_irqrestore(&rtp->cbs_gbl_lock, flags);
if (rcu_task_cb_adjust)
pr_info("%s: Setting adjustable number of callback queues.\n", __func__);
rcu_task_cpu_ids = maxcpu + 1;
if (lim > rcu_task_cpu_ids)
lim = rcu_task_cpu_ids;
shift = ilog2(rcu_task_cpu_ids / lim);
if (((rcu_task_cpu_ids - 1) >> shift) >= lim)
shift++;
WRITE_ONCE(rtp->percpu_enqueue_shift, shift);
WRITE_ONCE(rtp->percpu_dequeue_lim, lim);
smp_store_release(&rtp->percpu_enqueue_lim, lim);
pr_info("%s: Setting shift to %d and lim to %d rcu_task_cb_adjust=%d rcu_task_cpu_ids=%d.\n",
rtp->name, data_race(rtp->percpu_enqueue_shift), data_race(rtp->percpu_enqueue_lim),
rcu_task_cb_adjust, rcu_task_cpu_ids);
pr_info("%s: Setting shift to %d and lim to %d.\n", __func__, data_race(rtp->percpu_enqueue_shift), data_race(rtp->percpu_enqueue_lim));
}
// IRQ-work handler that does deferred wakeup for call_rcu_tasks_generic().
@ -327,7 +307,7 @@ static void call_rcu_tasks_generic(struct rcu_head *rhp, rcu_callback_t func,
rtpcp->rtp_n_lock_retries = 0;
}
if (rcu_task_cb_adjust && ++rtpcp->rtp_n_lock_retries > rcu_task_contend_lim &&
READ_ONCE(rtp->percpu_enqueue_lim) != rcu_task_cpu_ids)
READ_ONCE(rtp->percpu_enqueue_lim) != nr_cpu_ids)
needadjust = true; // Defer adjustment to avoid deadlock.
}
if (!rcu_segcblist_is_enabled(&rtpcp->cblist)) {
@ -340,10 +320,10 @@ static void call_rcu_tasks_generic(struct rcu_head *rhp, rcu_callback_t func,
raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags);
if (unlikely(needadjust)) {
raw_spin_lock_irqsave(&rtp->cbs_gbl_lock, flags);
if (rtp->percpu_enqueue_lim != rcu_task_cpu_ids) {
if (rtp->percpu_enqueue_lim != nr_cpu_ids) {
WRITE_ONCE(rtp->percpu_enqueue_shift, 0);
WRITE_ONCE(rtp->percpu_dequeue_lim, rcu_task_cpu_ids);
smp_store_release(&rtp->percpu_enqueue_lim, rcu_task_cpu_ids);
WRITE_ONCE(rtp->percpu_dequeue_lim, nr_cpu_ids);
smp_store_release(&rtp->percpu_enqueue_lim, nr_cpu_ids);
pr_info("Switching %s to per-CPU callback queuing.\n", rtp->name);
}
raw_spin_unlock_irqrestore(&rtp->cbs_gbl_lock, flags);
@ -414,8 +394,6 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp)
int needgpcb = 0;
for (cpu = 0; cpu < smp_load_acquire(&rtp->percpu_dequeue_lim); cpu++) {
if (!cpu_possible(cpu))
continue;
struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu);
/* Advance and accelerate any new callbacks. */
@ -448,7 +426,7 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp)
if (rcu_task_cb_adjust && ncbs <= rcu_task_collapse_lim) {
raw_spin_lock_irqsave(&rtp->cbs_gbl_lock, flags);
if (rtp->percpu_enqueue_lim > 1) {
WRITE_ONCE(rtp->percpu_enqueue_shift, order_base_2(rcu_task_cpu_ids));
WRITE_ONCE(rtp->percpu_enqueue_shift, order_base_2(nr_cpu_ids));
smp_store_release(&rtp->percpu_enqueue_lim, 1);
rtp->percpu_dequeue_gpseq = get_state_synchronize_rcu();
gpdone = false;
@ -463,9 +441,7 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp)
pr_info("Completing switch %s to CPU-0 callback queuing.\n", rtp->name);
}
if (rtp->percpu_dequeue_lim == 1) {
for (cpu = rtp->percpu_dequeue_lim; cpu < rcu_task_cpu_ids; cpu++) {
if (!cpu_possible(cpu))
continue;
for (cpu = rtp->percpu_dequeue_lim; cpu < nr_cpu_ids; cpu++) {
struct rcu_tasks_percpu *rtpcp = per_cpu_ptr(rtp->rtpcpu, cpu);
WARN_ON_ONCE(rcu_segcblist_n_cbs(&rtpcp->cblist));
@ -480,32 +456,30 @@ static int rcu_tasks_need_gpcb(struct rcu_tasks *rtp)
// Advance callbacks and invoke any that are ready.
static void rcu_tasks_invoke_cbs(struct rcu_tasks *rtp, struct rcu_tasks_percpu *rtpcp)
{
int cpu;
int cpunext;
int cpuwq;
unsigned long flags;
int len;
int index;
struct rcu_head *rhp;
struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
struct rcu_tasks_percpu *rtpcp_next;
index = rtpcp->index * 2 + 1;
if (index < num_possible_cpus()) {
rtpcp_next = rtp->rtpcp_array[index];
if (rtpcp_next->cpu < smp_load_acquire(&rtp->percpu_dequeue_lim)) {
cpuwq = rcu_cpu_beenfullyonline(rtpcp_next->cpu) ? rtpcp_next->cpu : WORK_CPU_UNBOUND;
cpu = rtpcp->cpu;
cpunext = cpu * 2 + 1;
if (cpunext < smp_load_acquire(&rtp->percpu_dequeue_lim)) {
rtpcp_next = per_cpu_ptr(rtp->rtpcpu, cpunext);
cpuwq = rcu_cpu_beenfullyonline(cpunext) ? cpunext : WORK_CPU_UNBOUND;
queue_work_on(cpuwq, system_wq, &rtpcp_next->rtp_work);
cpunext++;
if (cpunext < smp_load_acquire(&rtp->percpu_dequeue_lim)) {
rtpcp_next = per_cpu_ptr(rtp->rtpcpu, cpunext);
cpuwq = rcu_cpu_beenfullyonline(cpunext) ? cpunext : WORK_CPU_UNBOUND;
queue_work_on(cpuwq, system_wq, &rtpcp_next->rtp_work);
index++;
if (index < num_possible_cpus()) {
rtpcp_next = rtp->rtpcp_array[index];
if (rtpcp_next->cpu < smp_load_acquire(&rtp->percpu_dequeue_lim)) {
cpuwq = rcu_cpu_beenfullyonline(rtpcp_next->cpu) ? rtpcp_next->cpu : WORK_CPU_UNBOUND;
queue_work_on(cpuwq, system_wq, &rtpcp_next->rtp_work);
}
}
}
}
if (rcu_segcblist_empty(&rtpcp->cblist))
if (rcu_segcblist_empty(&rtpcp->cblist) || !cpu_possible(cpu))
return;
raw_spin_lock_irqsave_rcu_node(rtpcp, flags);
rcu_segcblist_advance(&rtpcp->cblist, rcu_seq_current(&rtp->tasks_gp_seq));