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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: Adrian Hunter <adrian.hunter@nokia.com> Acked-by: Matt 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -461,16 +461,18 @@ int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)
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while (1) {
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set_current_state(TASK_UNINTERRUPTIBLE);
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stop = abort ? atomic_read(abort) : 0;
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if (stop || !host->claimed)
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if (stop || !host->claimed || host->claimer == current)
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break;
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spin_unlock_irqrestore(&host->lock, flags);
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schedule();
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spin_lock_irqsave(&host->lock, flags);
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}
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set_current_state(TASK_RUNNING);
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if (!stop)
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if (!stop) {
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host->claimed = 1;
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else
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host->claimer = current;
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host->claim_cnt += 1;
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} else
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wake_up(&host->wq);
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spin_unlock_irqrestore(&host->lock, flags);
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remove_wait_queue(&host->wq, &wait);
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@ -481,30 +483,44 @@ int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)
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EXPORT_SYMBOL(__mmc_claim_host);
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static int mmc_try_claim_host(struct mmc_host *host)
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/**
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* mmc_try_claim_host - try exclusively to claim a host
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* @host: mmc host to claim
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*
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* Returns %1 if the host is claimed, %0 otherwise.
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*/
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int mmc_try_claim_host(struct mmc_host *host)
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{
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int claimed_host = 0;
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unsigned long flags;
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spin_lock_irqsave(&host->lock, flags);
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if (!host->claimed) {
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if (!host->claimed || host->claimer == current) {
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host->claimed = 1;
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host->claimer = current;
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host->claim_cnt += 1;
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claimed_host = 1;
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}
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spin_unlock_irqrestore(&host->lock, flags);
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return claimed_host;
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}
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EXPORT_SYMBOL(mmc_try_claim_host);
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static void mmc_do_release_host(struct mmc_host *host)
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{
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unsigned long flags;
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spin_lock_irqsave(&host->lock, flags);
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host->claimed = 0;
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if (--host->claim_cnt) {
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/* Release for nested claim */
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spin_unlock_irqrestore(&host->lock, flags);
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} else {
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host->claimed = 0;
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host->claimer = NULL;
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spin_unlock_irqrestore(&host->lock, flags);
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wake_up(&host->wq);
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}
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}
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void mmc_host_deeper_disable(struct work_struct *work)
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{
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@ -139,6 +139,7 @@ extern unsigned int mmc_align_data_size(struct mmc_card *, unsigned int);
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extern int __mmc_claim_host(struct mmc_host *host, atomic_t *abort);
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extern void mmc_release_host(struct mmc_host *host);
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extern int mmc_try_claim_host(struct mmc_host *host);
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/**
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* mmc_claim_host - exclusively claim a host
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@ -182,6 +182,8 @@ struct mmc_host {
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struct mmc_card *card; /* device attached to this host */
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wait_queue_head_t wq;
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struct task_struct *claimer; /* task that has host claimed */
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int claim_cnt; /* "claim" nesting count */
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struct delayed_work detect;
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