Commit 8279171a authored Jul 14, 2011 by Shyam Iyer Committed by David S. Miller Jul 15, 2011

Separate handling of irq type flags variable from the irq_flags request_irq variable

Commit 5f77898d does not completely
fix the problem of handling allocations with irqs disabled.. The
below patch on top of it fixes the problem completely.

Based on review by "Ivan Vecera" <ivecera@redhat.com>..
"
Small note, the root of the problem was that non-atomic allocation was requested with IRQs disabled. Your patch description does not contain wwhy were the IRQs disabled.

The function bnad_mbox_irq_alloc incorrectly uses 'flags' var for two different things, 1) to save current CPU flags and 2) for request_irq
call.
First the spin_lock_irqsave disables the IRQs and saves _all_ CPU flags (including one that enables/disables interrupts) to 'flags'. Then the 'flags' is overwritten by 0 or 0x80 (IRQF_SHARED). Finally the spin_unlock_irqrestore should restore saved flags, but these flags are now either 0x00 or 0x80. The interrupt bit value in flags register on x86 arch is 0x100.
This means that the interrupt bit is zero (IRQs disabled) after spin_unlock_irqrestore so the request_irq function is called with disabled interrupts.
"

Signed-off-by: Shyam Iyer <shyam_iyer@dell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent ecae42d3

drivers/net/bna/bnad.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -1109,7 +1109,7 @@ bnad_mbox_irq_alloc(struct bnad *bnad,
		struct bna_intr_info *intr_info)
		{
		int err = 0;
		unsigned long irq_flags = 0, flags;
		unsigned long irq_flags, flags;
		u32 irq;
		irq_handler_t irq_handler;

		@@ -1123,6 +1123,7 @@ bnad_mbox_irq_alloc(struct bnad *bnad,
		if (bnad->cfg_flags & BNAD_CF_MSIX) {
		irq_handler = (irq_handler_t)bnad_msix_mbox_handler;
		irq = bnad->msix_table[bnad->msix_num - 1].vector;
		irq_flags = 0;
		intr_info->intr_type = BNA_INTR_T_MSIX;
		intr_info->idl[0].vector = bnad->msix_num - 1;
		} else {
		@@ -1133,7 +1134,6 @@ bnad_mbox_irq_alloc(struct bnad *bnad,
		/* intr_info->idl.vector = 0 ? */
		}
		spin_unlock_irqrestore(&bnad->bna_lock, flags);
		flags = irq_flags;
		sprintf(bnad->mbox_irq_name, "%s", BNAD_NAME);

		/*
		@@ -1144,7 +1144,7 @@ bnad_mbox_irq_alloc(struct bnad *bnad,

		BNAD_UPDATE_CTR(bnad, mbox_intr_disabled);

		err = request_irq(irq, irq_handler, flags,
		err = request_irq(irq, irq_handler, irq_flags,
		bnad->mbox_irq_name, bnad);

		if (err) {

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