tasklets API update for v5.9-rc1

- Prepare for tasklet API modernization (Romain Perier, Allen Pais, Kees Cook)
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Merge tag 'tasklets-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull tasklets API update from Kees Cook:
 "These are the infrastructure updates needed to support converting the
  tasklet API to something more modern (and hopefully for removal
  further down the road).

  There is a 300-patch series waiting in the wings to get set out to
  subsystem maintainers, but these changes need to be present in the
  kernel first. Since this has some treewide changes, I carried this
  series for -next instead of paining Thomas with it in -tip, but it's
  got his Ack.

  This is similar to the timer_struct modernization from a while back,
  but not nearly as messy (I hope). :)

   - Prepare for tasklet API modernization (Romain Perier, Allen Pais,
     Kees Cook)"

* tag 'tasklets-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  tasklet: Introduce new initialization API
  treewide: Replace DECLARE_TASKLET() with DECLARE_TASKLET_OLD()
  usb: gadget: udc: Avoid tasklet passing a global

drivers/input/keyboard/omap-keypad.c

@@ -46,7 +46,7 @@ struct omap_kp {
 	unsigned short keymap[];
 };
 
-static DECLARE_TASKLET_DISABLED(kp_tasklet, omap_kp_tasklet, 0);
+static DECLARE_TASKLET_DISABLED_OLD(kp_tasklet, omap_kp_tasklet);
 
 static unsigned int *row_gpios;
 static unsigned int *col_gpios;

drivers/input/serio/hil_mlc.c

@@ -77,7 +77,7 @@ static struct timer_list	hil_mlcs_kicker;
 static int			hil_mlcs_probe;
 
 static void hil_mlcs_process(unsigned long unused);
-static DECLARE_TASKLET_DISABLED(hil_mlcs_tasklet, hil_mlcs_process, 0);
+static DECLARE_TASKLET_DISABLED_OLD(hil_mlcs_tasklet, hil_mlcs_process);
 
 
 /* #define HIL_MLC_DEBUG */

drivers/net/wan/farsync.c

@@ -569,8 +569,8 @@ static void do_bottom_half_rx(struct fst_card_info *card);
 static void fst_process_tx_work_q(unsigned long work_q);
 static void fst_process_int_work_q(unsigned long work_q);
 
-static DECLARE_TASKLET(fst_tx_task, fst_process_tx_work_q, 0);
-static DECLARE_TASKLET(fst_int_task, fst_process_int_work_q, 0);
+static DECLARE_TASKLET_OLD(fst_tx_task, fst_process_tx_work_q);
+static DECLARE_TASKLET_OLD(fst_int_task, fst_process_int_work_q);
 
 static struct fst_card_info *fst_card_array[FST_MAX_CARDS];
 static spinlock_t fst_work_q_lock;

drivers/s390/crypto/ap_bus.c

@@ -92,7 +92,7 @@ static DECLARE_WORK(ap_scan_work, ap_scan_bus);
  * Tasklet & timer for AP request polling and interrupts
  */
 static void ap_tasklet_fn(unsigned long);
-static DECLARE_TASKLET(ap_tasklet, ap_tasklet_fn, 0);
+static DECLARE_TASKLET_OLD(ap_tasklet, ap_tasklet_fn);
 static DECLARE_WAIT_QUEUE_HEAD(ap_poll_wait);
 static struct task_struct *ap_poll_kthread;
 static DEFINE_MUTEX(ap_poll_thread_mutex);

drivers/staging/most/dim2/dim2.c

@@ -46,7 +46,7 @@ MODULE_PARM_DESC(fcnt, "Num of frames per sub-buffer for sync channels as a powe
 static DEFINE_SPINLOCK(dim_lock);
 
 static void dim2_tasklet_fn(unsigned long data);
-static DECLARE_TASKLET(dim2_tasklet, dim2_tasklet_fn, 0);
+static DECLARE_TASKLET_OLD(dim2_tasklet, dim2_tasklet_fn);
 
 /**
  * struct hdm_channel - private structure to keep channel specific data

drivers/staging/octeon/ethernet-tx.c

@@ -41,7 +41,7 @@
 #endif
 
 static void cvm_oct_tx_do_cleanup(unsigned long arg);
-static DECLARE_TASKLET(cvm_oct_tx_cleanup_tasklet, cvm_oct_tx_do_cleanup, 0);
+static DECLARE_TASKLET_OLD(cvm_oct_tx_cleanup_tasklet, cvm_oct_tx_do_cleanup);
 
 /* Maximum number of SKBs to try to free per xmit packet. */
 #define MAX_SKB_TO_FREE (MAX_OUT_QUEUE_DEPTH * 2)

drivers/tty/vt/keyboard.c

@@ -1236,7 +1236,7 @@ static void kbd_bh(unsigned long dummy)
 	}
 }
 
-DECLARE_TASKLET_DISABLED(keyboard_tasklet, kbd_bh, 0);
+DECLARE_TASKLET_DISABLED_OLD(keyboard_tasklet, kbd_bh);
 
 #if defined(CONFIG_X86) || defined(CONFIG_IA64) || defined(CONFIG_ALPHA) ||\
     defined(CONFIG_MIPS) || defined(CONFIG_PPC) || defined(CONFIG_SPARC) ||\

drivers/usb/gadget/udc/snps_udc_core.c

@@ -96,9 +96,7 @@ static int stop_pollstall_timer;
 static DECLARE_COMPLETION(on_pollstall_exit);
 
 /* tasklet for usb disconnect */
-static DECLARE_TASKLET(disconnect_tasklet, udc_tasklet_disconnect,
-		(unsigned long) &udc);
-
+static DECLARE_TASKLET_OLD(disconnect_tasklet, udc_tasklet_disconnect);
 
 /* endpoint names used for print */
 static const char ep0_string[] = "ep0in";
@@ -1661,7 +1659,7 @@ static void usb_disconnect(struct udc *dev)
 /* Tasklet for disconnect to be outside of interrupt context */
 static void udc_tasklet_disconnect(unsigned long par)
 {
-	struct udc *dev = (struct udc *)(*((struct udc **) par));
+	struct udc *dev = udc;
 	u32 tmp;
 
 	DBG(dev, "Tasklet disconnect\n");

drivers/usb/host/fhci-sched.c

@@ -677,7 +677,7 @@ static void process_done_list(unsigned long data)
 	enable_irq(fhci_to_hcd(fhci)->irq);
 }
 
-DECLARE_TASKLET(fhci_tasklet, process_done_list, 0);
+DECLARE_TASKLET_OLD(fhci_tasklet, process_done_list);
 
 /* transfer complted callback */
 u32 fhci_transfer_confirm_callback(struct fhci_hcd *fhci)

include/linux/interrupt.h

@@ -585,6 +585,9 @@ static inline struct task_struct *this_cpu_ksoftirqd(void)
 
 /* Tasklets --- multithreaded analogue of BHs.
 
+   This API is deprecated. Please consider using threaded IRQs instead:
+   https://lore.kernel.org/lkml/20200716081538.2sivhkj4hcyrusem@linutronix.de
+
    Main feature differing them of generic softirqs: tasklet
    is running only on one CPU simultaneously.
 
@@ -608,16 +611,42 @@ struct tasklet_struct
 	struct tasklet_struct *next;
 	unsigned long state;
 	atomic_t count;
-	void (*func)(unsigned long);
+	bool use_callback;
+	union {
+		void (*func)(unsigned long data);
+		void (*callback)(struct tasklet_struct *t);
+	};
 	unsigned long data;
 };
 
-#define DECLARE_TASKLET(name, func, data) \
-struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(0), func, data }
+#define DECLARE_TASKLET(name, _callback)		\
+struct tasklet_struct name = {				\
+	.count = ATOMIC_INIT(0),			\
+	.callback = _callback,				\
+	.use_callback = true,				\
+}
 
-#define DECLARE_TASKLET_DISABLED(name, func, data) \
-struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }
+#define DECLARE_TASKLET_DISABLED(name, _callback)	\
+struct tasklet_struct name = {				\
+	.count = ATOMIC_INIT(1),			\
+	.callback = _callback,				\
+	.use_callback = true,				\
+}
 
+#define from_tasklet(var, callback_tasklet, tasklet_fieldname)	\
+	container_of(callback_tasklet, typeof(*var), tasklet_fieldname)
+
+#define DECLARE_TASKLET_OLD(name, _func)		\
+struct tasklet_struct name = {				\
+	.count = ATOMIC_INIT(0),			\
+	.func = _func,					\
+}
+
+#define DECLARE_TASKLET_DISABLED_OLD(name, _func)	\
+struct tasklet_struct name = {				\
+	.count = ATOMIC_INIT(1),			\
+	.func = _func,					\
+}
 
 enum
 {
@@ -686,6 +715,8 @@ extern void tasklet_kill(struct tasklet_struct *t);
 extern void tasklet_kill_immediate(struct tasklet_struct *t, unsigned int cpu);
 extern void tasklet_init(struct tasklet_struct *t,
 			 void (*func)(unsigned long), unsigned long data);
+extern void tasklet_setup(struct tasklet_struct *t,
+			  void (*callback)(struct tasklet_struct *));
 
 /*
  * Autoprobing for irqs:

kernel/backtracetest.c

@@ -29,7 +29,7 @@ static void backtrace_test_irq_callback(unsigned long data)
 	complete(&backtrace_work);
 }
 
-static DECLARE_TASKLET(backtrace_tasklet, &backtrace_test_irq_callback, 0);
+static DECLARE_TASKLET_OLD(backtrace_tasklet, &backtrace_test_irq_callback);
 
 static void backtrace_test_irq(void)
 {

kernel/debug/debug_core.c

@@ -1068,7 +1068,7 @@ static void kgdb_tasklet_bpt(unsigned long ing)
 	atomic_set(&kgdb_break_tasklet_var, 0);
 }
 
-static DECLARE_TASKLET(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt, 0);
+static DECLARE_TASKLET_OLD(kgdb_tasklet_breakpoint, kgdb_tasklet_bpt);
 
 void kgdb_schedule_breakpoint(void)
 {

kernel/irq/resend.c

@@ -45,7 +45,7 @@ static void resend_irqs(unsigned long arg)
 }
 
 /* Tasklet to handle resend: */
-static DECLARE_TASKLET(resend_tasklet, resend_irqs, 0);
+static DECLARE_TASKLET_OLD(resend_tasklet, resend_irqs);
 
 static int irq_sw_resend(struct irq_desc *desc)
 {

kernel/softirq.c

@@ -553,7 +553,10 @@ static void tasklet_action_common(struct softirq_action *a,
 				if (!test_and_clear_bit(TASKLET_STATE_SCHED,
 							&t->state))
 					BUG();
-				t->func(t->data);
+				if (t->use_callback)
+					t->callback(t);
+				else
+					t->func(t->data);
 				tasklet_unlock(t);
 				continue;
 			}
@@ -579,6 +582,18 @@ static __latent_entropy void tasklet_hi_action(struct softirq_action *a)
 	tasklet_action_common(a, this_cpu_ptr(&tasklet_hi_vec), HI_SOFTIRQ);
 }
 
+void tasklet_setup(struct tasklet_struct *t,
+		   void (*callback)(struct tasklet_struct *))
+{
+	t->next = NULL;
+	t->state = 0;
+	atomic_set(&t->count, 0);
+	t->callback = callback;
+	t->use_callback = true;
+	t->data = 0;
+}
+EXPORT_SYMBOL(tasklet_setup);
+
 void tasklet_init(struct tasklet_struct *t,
 		  void (*func)(unsigned long), unsigned long data)
 {
@@ -586,6 +601,7 @@ void tasklet_init(struct tasklet_struct *t,
 	t->state = 0;
 	atomic_set(&t->count, 0);
 	t->func = func;
+	t->use_callback = false;
 	t->data = data;
 }
 EXPORT_SYMBOL(tasklet_init);

net/atm/pppoatm.c

@@ -393,7 +393,7 @@ static int pppoatm_assign_vcc(struct atm_vcc *atmvcc, void __user *arg)
 	 * Each PPPoATM instance has its own tasklet - this is just a
 	 * prototypical one used to initialize them
 	 */
-	static const DECLARE_TASKLET(tasklet_proto, pppoatm_wakeup_sender, 0);
+	static const DECLARE_TASKLET_OLD(tasklet_proto, pppoatm_wakeup_sender);
 	if (copy_from_user(&be, arg, sizeof be))
 		return -EFAULT;
 	if (be.encaps != PPPOATM_ENCAPS_AUTODETECT &&

net/iucv/iucv.c

@@ -105,7 +105,7 @@ static LIST_HEAD(iucv_task_queue);
  * The tasklet for fast delivery of iucv interrupts.
  */
 static void iucv_tasklet_fn(unsigned long);
-static DECLARE_TASKLET(iucv_tasklet, iucv_tasklet_fn,0);
+static DECLARE_TASKLET_OLD(iucv_tasklet, iucv_tasklet_fn);
 
 /*
  * Queue of interrupt buffers for delivery via a work queue

sound/drivers/pcsp/pcsp_lib.c

@@ -36,7 +36,7 @@ static void pcsp_call_pcm_elapsed(unsigned long priv)
 	}
 }
 
-static DECLARE_TASKLET(pcsp_pcm_tasklet, pcsp_call_pcm_elapsed, 0);
+static DECLARE_TASKLET_OLD(pcsp_pcm_tasklet, pcsp_call_pcm_elapsed);
 
 /* write the port and returns the next expire time in ns;
  * called at the trigger-start and in hrtimer callback