linux-kernel - [PATCH v3] irqchip/gicv3-its: Avoid memory over allocation for ITEs

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Date:   Tue,  7 Mar 2017 08:25:20 -0600
From:   Shanker Donthineni <shankerd@...eaurora.org>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Vikram Sethi <vikrams@...eaurora.org>,
        Shanker Donthineni <shankerd@...eaurora.org>
Subject: [PATCH v3] irqchip/gicv3-its: Avoid memory over allocation for ITEs

We are always allocating extra 255Bytes of memory to handle ITE
physical address alignment requirement. The kmalloc() satisfies
the ITE alignment since the ITS driver is requesting a minimum
size of ITS_ITT_ALIGN bytes.

Let's try to allocate the exact amount of memory that is required
for ITEs to avoid wastage.

Signed-off-by: Shanker Donthineni <shankerd@...eaurora.org>
---
v2: removed 'Change-Id: Ia8084189833f2081ff13c392deb5070c46a64038' from commit.
v3: changed from IITE to ITE.

 drivers/irqchip/irq-gic-v3-its.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 86bd428..5aeca78 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1329,8 +1329,13 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
 	 */
 	nr_ites = max(2UL, roundup_pow_of_two(nvecs));
 	sz = nr_ites * its->ite_size;
-	sz = max(sz, ITS_ITT_ALIGN) + ITS_ITT_ALIGN - 1;
+	sz = max(sz, ITS_ITT_ALIGN);
 	itt = kzalloc(sz, GFP_KERNEL);
+	if (itt && !IS_ALIGNED(virt_to_phys(itt), ITS_ITT_ALIGN)) {
+		kfree(itt);
+		itt = kzalloc(sz + ITS_ITT_ALIGN - 1, GFP_KERNEL);
+	}
+
 	lpi_map = its_lpi_alloc_chunks(nvecs, &lpi_base, &nr_lpis);
 	if (lpi_map)
 		col_map = kzalloc(sizeof(*col_map) * nr_lpis, GFP_KERNEL);
-- 
Qualcomm Datacenter Technologies, Inc. on behalf of the Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.