From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Sender: Grant Likely Subject: [PATCH 6/6] powerpc: use irq_alloc_desc() to manage irq allocations To: Michal Simek , Benjamin Herrenschmidt , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, Ralf Baechle , hpa@zytor.com, Dirk Brandewie , Thomas Gleixner From: Grant Likely Date: Thu, 28 Apr 2011 14:02:14 -0600 Message-ID: <20110428200214.8979.84221.stgit@ponder> In-Reply-To: <20110428192227.8979.49181.stgit@ponder> References: <20110428192227.8979.49181.stgit@ponder> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Cc: devicetree-discuss@lists.ozlabs.org, x86@kernel.org, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , This patch drops the architecture specific code for managing irq assignments and uses core code instead. *RFC* This patch is *not* ready for merging. The locking is messed up where the irq_map is still used to find out if a mapping is already established, but irq_alloc_desc() is now called before the irq_map is updated which creates a race condition. I've not completely sorted out how to solve this yet. The solution may very well be to convert the irq_big_lock to a mutex (but I'm not sure if anything that sleeps calls the affected code), and hold the mutex over the entire operation. Signed-off-by: Grant Likely --- arch/powerpc/kernel/irq.c | 51 ++++++++++++--------------------------------- 1 files changed, 14 insertions(+), 37 deletions(-) diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c index 0fb90ab..e4a6646 100644 --- a/arch/powerpc/kernel/irq.c +++ b/arch/powerpc/kernel/irq.c @@ -984,53 +984,29 @@ unsigned int irq_linear_revmap(struct irq_host *host, static unsigned int irq_alloc_virt(struct irq_host *host, unsigned int hint) { unsigned long flags; - unsigned int i, j, found = NO_IRQ; - int res; + int found; - raw_spin_lock_irqsave(&irq_big_lock, flags); - - /* Use hint for 1 interrupt if any */ - if (hint >= NUM_ISA_INTERRUPTS && - hint < irq_virq_count && irq_map[hint].host == NULL) { - found = hint; - goto hint_found; - } - - /* Look for a free virq in the allocatable (non-legacy) space */ - for (i = NUM_ISA_INTERRUPTS, j = 0; i < irq_virq_count; i++) { - if (irq_map[i].host == NULL) { - found = i; - break; - } - } - if (found == NO_IRQ) { - raw_spin_unlock_irqrestore(&irq_big_lock, flags); + /* + * Find an unused interrupt. First, attempt to allocate + * 'hint'. If that fails, then just allocate any free one. + */ + found = irq_alloc_desc_at(hint, 0); + if (found <= NO_IRQ) + found = irq_alloc_desc(0); + if (found <= NO_IRQ) { + pr_debug("irq: -> allocating desc failed\n"); return NO_IRQ; } - hint_found: + + raw_spin_lock_irqsave(&irq_big_lock, flags); irq_map[found].hwirq = host->inval_irq; smp_wmb(); irq_map[found].host = host; raw_spin_unlock_irqrestore(&irq_big_lock, flags); - res = irq_alloc_desc_at(found, 0); - if (res != found) { - pr_debug("irq: -> allocating desc failed\n"); - goto error_desc; - } - irq_clear_status_flags(found, IRQ_NOREQUEST); return found; - - error_desc: - raw_spin_lock_irqsave(&irq_big_lock, flags); - host = irq_map[found].host; - irq_map[found].hwirq = host->inval_irq; - smp_wmb(); - irq_map[found].host = NULL; - raw_spin_unlock_irqrestore(&irq_big_lock, flags); - return NO_IRQ; } /** @@ -1051,13 +1027,14 @@ static void irq_free_virt(unsigned int virq) return; } - irq_free_descs(virq, 1); raw_spin_lock_irqsave(&irq_big_lock, flags); host = irq_map[virq].host; irq_map[virq].hwirq = host->inval_irq; smp_wmb(); irq_map[virq].host = NULL; raw_spin_unlock_irqrestore(&irq_big_lock, flags); + + irq_free_descs(virq, 1); } int arch_early_irq_init(void)