From: Suzuki.Poulose@arm•com (Suzuki K Poulose)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH V3 09/18] coresight: tmc: allocating memory when needed
Date: Mon, 25 Apr 2016 11:20:15 +0100 [thread overview]
Message-ID: <571DEF5F.5060109@arm.com> (raw)
In-Reply-To: <1461345255-11758-10-git-send-email-mathieu.poirier@linaro.org>
On 22/04/16 18:14, Mathieu Poirier wrote:
> static int tmc_enable_etf_sink(struct coresight_device *csdev, u32 mode)
> {
> + bool used = false;
> + char *buf = NULL;
> unsigned long flags;
> struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>
> + /* This shouldn't be happening */
> + if (WARN_ON(mode != CS_MODE_SYSFS))
> + return -EINVAL;
> +
> + /*
> + * If a buffer is already allocated *keep holding* the lock and
> + * jump to the fast path. Otherwise release the lock and allocate
> + * memory to work with.
> + */
> spin_lock_irqsave(&drvdata->spinlock, flags);
> + if (drvdata->buf)
> + goto fast_path;
> +
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> +
> + /* Allocating the memory here while outside of the spinlock */
> + buf = kzalloc(drvdata->size, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + /* Let's try again */
> + spin_lock_irqsave(&drvdata->spinlock, flags);
> +fast_path:
nit: As I mentioned in the previous series, could we not avoid the goto in the middle of the
function,by doing :
if (!drvdata->buf) {
unlock();
buf = alloc();
if (!buf) return -ENOMEM;
lock();
}
> if (drvdata->reading) {
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
> + /*
> + * Free allocated memory outside of the spinlock. There is
> + * no need to assert the validity of 'buf' since calling
> + * kfree(NULL) is safe.
> + */
> + kfree(buf);
> return -EBUSY;
> }
It would be good to unify the exit points as we do similar steps.
if (drvdata->reading) {
rc = -EBUSY;
goto out;
}
>
> + /*
> + * If drvdata::buf isn't NULL, memory was allocated for a previous
> + * trace run but wasn't read. If so simply zero-out the memory.
> + * Otherwise use the memory allocated above.
> + *
> + * The memory is freed when users read the buffer using the
> + * /dev/xyz.{etf|etb} interface. See tmc_read_unprepare_etf() for
> + * details.
> + */
> + if (drvdata->buf) {
> + memset(drvdata->buf, 0, drvdata->size);
> + } else {
> + used = true;
> + drvdata->buf = buf;
> + }
> +
> tmc_etb_enable_hw(drvdata);
> drvdata->enable = true;
out:
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>
> + /* Free memory outside the spinlock if need be */
> + if (!used && buf)
> + kfree(buf);
> +
if (!rc)
dev_info(drvdata->dev, "TMC-ETB/ETF enabled\n");
return rc
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 3483d139a4ac..474c70c089f3 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode)
> {
> + bool used = false;
> unsigned long flags;
> + void __iomem *vaddr = NULL;
> + dma_addr_t paddr;
> struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>
> + /* This shouldn't be happening */
> + if (WARN_ON(mode != CS_MODE_SYSFS))
> + return -EINVAL;
> +
> + /*
> + * If a buffer is already allocated *keep holding* the lock and
> + * jump to the fast path. Otherwise release the lock and allocate
> + * memory to work with.
> + */
> + spin_lock_irqsave(&drvdata->spinlock, flags);
> + if (drvdata->vaddr)
> + goto fast_path;
> +
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> +
> + /*
> + * Contiguous memory can't be allocated while a spinlock is held.
> + * As such allocate memory here and free it if a buffer has already
> + * been allocated (from a previous session).
> + */
> + vaddr = dma_alloc_coherent(drvdata->dev, drvdata->size,
> + &paddr, GFP_KERNEL);
> + if (!vaddr)
> + return -ENOMEM;
> +
> + /* Let's try again */
> spin_lock_irqsave(&drvdata->spinlock, flags);
> +fast_path:
nit: Same as above.
I am not too particular about the above changes, but would be good to have them
reader friendly.
Either way,
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm•com>
Suzuki
next prev parent reply other threads:[~2016-04-25 10:20 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-22 17:13 [PATCH V3 00/18] coresight: tmc: make driver usable by Perf Mathieu Poirier
2016-04-22 17:13 ` [PATCH V3 01/18] coresight: tmc: modifying naming convention Mathieu Poirier
2016-04-22 17:13 ` [PATCH V3 02/18] coresight: tmc: waiting for TMCReady bit before programming Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 03/18] coresight: tmc: re-implementing tmc_read_prepare/unprepare() functions Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 04/18] coresight: tmc: clearly define number of transfers per burst Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 05/18] coresight: tmc: introducing new header file Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 06/18] coresight: tmc: cleaning up " Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 07/18] coresight: tmc: splitting driver in ETB/ETF and ETR components Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 08/18] coresight: tmc: making prepare/unprepare functions generic Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 09/18] coresight: tmc: allocating memory when needed Mathieu Poirier
2016-04-25 10:20 ` Suzuki K Poulose [this message]
2016-04-25 14:24 ` Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 10/18] coresight: tmc: getting the right read_count on tmc_open() Mathieu Poirier
2016-04-25 10:47 ` Suzuki K Poulose
2016-04-25 14:25 ` Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 11/18] coresight: tmc: adding mode of operation for link/sinks Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 12/18] coresight: tmc: dump system memory content only when needed Mathieu Poirier
2016-04-25 11:16 ` Suzuki K Poulose
2016-04-25 14:38 ` Mathieu Poirier
2016-04-25 14:49 ` Suzuki K Poulose
2016-04-22 17:14 ` [PATCH V3 13/18] coresight: tmc: make sysFS and Perf mode mutually exclusive Mathieu Poirier
2016-04-25 14:32 ` Suzuki K Poulose
2016-04-25 14:48 ` Mathieu Poirier
2016-04-25 14:52 ` Suzuki K Poulose
2016-04-25 15:05 ` Mathieu Poirier
2016-04-25 15:11 ` Suzuki K Poulose
2016-04-25 15:18 ` Mathieu Poirier
2016-04-26 9:23 ` Suzuki K Poulose
2016-04-22 17:14 ` [PATCH V3 14/18] coresight: tmc: keep track of memory width Mathieu Poirier
2016-04-25 14:41 ` Suzuki K Poulose
2016-04-25 14:55 ` Mathieu Poirier
2016-04-25 15:09 ` Suzuki K Poulose
2016-04-25 15:25 ` Mathieu Poirier
2016-04-25 15:28 ` Suzuki K Poulose
2016-04-22 17:14 ` [PATCH V3 15/18] coresight: moving struct cs_buffers to header file Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 16/18] coresight: tmc: implementing TMC-ETF AUX space API Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 17/18] coresight: tmc: implementing TMC-ETR " Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 18/18] coresight: configuring ETF in FIFO mode when acting as link Mathieu Poirier
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