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Commit 319a3f14 authored by Adrian Hunter's avatar Adrian Hunter Committed by Linus Torvalds
Browse files

mmc: allow host claim / release nesting 



This change allows the MMC host to be claimed in situations where the host
may or may not have already been claimed.  Also 'mmc_try_claim_host()' is
now exported.

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@nokia.com>
Acked-by: default avatarMatt Fleming <matt@console-pimps.org>
Cc: Ian Molton <ian@mnementh.co.uk>
Cc: "Roberto A. Foglietta" <roberto.foglietta@gmail.com>
Cc: Jarkko Lavinen <jarkko.lavinen@nokia.com>
Cc: Denis Karpov <ext-denis.2.karpov@nokia.com>
Cc: Pierre Ossman <pierre@ossman.eu>
Cc: Philip Langdale <philipl@overt.org>
Cc: "Madhusudhan" <madhu.cr@ti.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8ea926b2

drivers/mmc/core/core.c

+25 −9
Original line number Diff line number Diff line
@@ -461,16 +461,18 @@ int __mmc_claim_host(struct mmc_host *host, atomic_t *abort) 
	while (1) {

		set_current_state(TASK_UNINTERRUPTIBLE);

		stop = abort ? atomic_read(abort) : 0;

		if (stop || !host->claimed)

		if (stop || !host->claimed || host->claimer == current)

			break;

		spin_unlock_irqrestore(&host->lock, flags);

		schedule();

		spin_lock_irqsave(&host->lock, flags);

	}

	set_current_state(TASK_RUNNING);

	if (!stop)

	if (!stop) {

		host->claimed = 1;

	else

		host->claimer = current;

		host->claim_cnt += 1;

	} else

		wake_up(&host->wq);

	spin_unlock_irqrestore(&host->lock, flags);

	remove_wait_queue(&host->wq, &wait);
@@ -481,30 +483,44 @@ int __mmc_claim_host(struct mmc_host *host, atomic_t *abort) 


EXPORT_SYMBOL(__mmc_claim_host);



static int mmc_try_claim_host(struct mmc_host *host)

/**

 *	mmc_try_claim_host - try exclusively to claim a host

 *	@host: mmc host to claim

 *

 *	Returns %1 if the host is claimed, %0 otherwise.

 */

int mmc_try_claim_host(struct mmc_host *host)

{

	int claimed_host = 0;

	unsigned long flags;



	spin_lock_irqsave(&host->lock, flags);

	if (!host->claimed) {

	if (!host->claimed || host->claimer == current) {

		host->claimed = 1;

		host->claimer = current;

		host->claim_cnt += 1;

		claimed_host = 1;

	}

	spin_unlock_irqrestore(&host->lock, flags);

	return claimed_host;

}

EXPORT_SYMBOL(mmc_try_claim_host);



static void mmc_do_release_host(struct mmc_host *host)

{

	unsigned long flags;



	spin_lock_irqsave(&host->lock, flags);

	if (--host->claim_cnt) {

		/* Release for nested claim */

		spin_unlock_irqrestore(&host->lock, flags);

	} else {

		host->claimed = 0;

		host->claimer = NULL;

		spin_unlock_irqrestore(&host->lock, flags);



		wake_up(&host->wq);

	}

}



void mmc_host_deeper_disable(struct work_struct *work)

{

include/linux/mmc/core.h

+1 −0
Original line number Diff line number Diff line
@@ -139,6 +139,7 @@ extern unsigned int mmc_align_data_size(struct mmc_card *, unsigned int); 


extern int __mmc_claim_host(struct mmc_host *host, atomic_t *abort);

extern void mmc_release_host(struct mmc_host *host);

extern int mmc_try_claim_host(struct mmc_host *host);



/**

 *	mmc_claim_host - exclusively claim a host

include/linux/mmc/host.h

+2 −0
Original line number Diff line number Diff line
@@ -182,6 +182,8 @@ struct mmc_host { 
	struct mmc_card		*card;		/* device attached to this host */



	wait_queue_head_t	wq;

	struct task_struct	*claimer;	/* task that has host claimed */

	int			claim_cnt;	/* "claim" nesting count */



	struct delayed_work	detect;