Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751923AbaAXQle (ORCPT ); Fri, 24 Jan 2014 11:41:34 -0500 Received: from mail-ie0-f182.google.com ([209.85.223.182]:39067 "EHLO mail-ie0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751839AbaAXQlc (ORCPT ); Fri, 24 Jan 2014 11:41:32 -0500 From: =?UTF-8?q?Adrien=20Verg=C3=A9?= To: Russell King Cc: =?UTF-8?q?Adrien=20Verg=C3=A9?= , Catalin Marinas , Will Deacon , Ben Dooks , "zhangwei(Jovi)" , Andrew Morton , Randy Dunlap , Mathieu Poirier , Christopher Covington , Dirk Behme , Michel Dagenais , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH V2 6/6] ARM CoreSight: ETM: Allocate a trace buffer only when necessary Date: Fri, 24 Jan 2014 11:40:56 -0500 Message-Id: <1390581656-16372-7-git-send-email-adrienverge@gmail.com> X-Mailer: git-send-email 1.8.5.2 In-Reply-To: <1390581656-16372-1-git-send-email-adrienverge@gmail.com> References: <1390581656-16372-1-git-send-email-adrienverge@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some user applications try to retrieve trace data often, there is no need to call vmalloc() when there is 0 byte to fetch. Signed-off-by: Adrien Vergé --- arch/arm/kernel/etm.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/arch/arm/kernel/etm.c b/arch/arm/kernel/etm.c index 54b5128..bc97240 100644 --- a/arch/arm/kernel/etm.c +++ b/arch/arm/kernel/etm.c @@ -309,7 +309,7 @@ static ssize_t etb_read(struct file *file, char __user *data, long length; struct tracectx *t = file->private_data; u32 first = 0; - u32 *buf; + u32 *buf = NULL; mutex_lock(&t->mutex); @@ -327,12 +327,14 @@ static ssize_t etb_read(struct file *file, char __user *data, etb_writel(t, first, ETBR_READADDR); length = min(total * 4, (int)len); - buf = vmalloc(length); + if (length != 0) + buf = vmalloc(length); dev_dbg(t->dev, "ETB buffer length: %d\n", total); dev_dbg(t->dev, "ETB status reg: %x\n", etb_readl(t, ETBR_STATUS)); - for (i = 0; i < length / 4; i++) - buf[i] = etb_readl(t, ETBR_READMEM); + if (buf) + for (i = 0; i < length / 4; i++) + buf[i] = etb_readl(t, ETBR_READMEM); /* the only way to deassert overflow bit in ETB status is this */ etb_writel(t, 1, ETBR_CTRL); @@ -345,7 +347,8 @@ static ssize_t etb_read(struct file *file, char __user *data, etb_lock(t); length -= copy_to_user(data, buf, length); - vfree(buf); + if (buf) + vfree(buf); out: mutex_unlock(&t->mutex); -- 1.8.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/