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Groups > linux.kernel > #1373570 > unrolled thread
| Started by | Suzuki K Poulose <Suzuki.Poulose@arm.com> |
|---|---|
| First post | 2016-04-07 19:00 +0200 |
| Last post | 2016-04-08 17:30 +0200 |
| Articles | 2 — 2 participants |
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Re: [PATCH 08/14] coresight: tmc: allocating memory when needed Suzuki K Poulose <Suzuki.Poulose@arm.com> - 2016-04-07 19:00 +0200
Re: [PATCH 08/14] coresight: tmc: allocating memory when needed Mathieu Poirier <mathieu.poirier@linaro.org> - 2016-04-08 17:30 +0200
| From | Suzuki K Poulose <Suzuki.Poulose@arm.com> |
|---|---|
| Date | 2016-04-07 19:00 +0200 |
| Subject | Re: [PATCH 08/14] coresight: tmc: allocating memory when needed |
| Message-ID | <rllrJ-6RI-37@gated-at.bofh.it> |
On 22/03/16 20:23, Mathieu Poirier wrote:
> In it's current form the TMC probe() function allocates
> trace buffer memory at boot time, event if coresight isn't
> used. This is highly inefficient since trace buffers can
> occupy a lot of memory that could be used otherwised.
>
> This patch allocates trace buffers on the fly, when the
> coresight subsytem is sollicited. Allocated buffers are
nit: *subsystem* is *solicited*.
> released when traces are read using the device descriptors
> under /dev.
>
> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> ---
> drivers/hwtracing/coresight/coresight-tmc-etf.c | 97 ++++++++++++++++++++-----
> drivers/hwtracing/coresight/coresight-tmc-etr.c | 97 ++++++++++++++++++++++---
> drivers/hwtracing/coresight/coresight-tmc.c | 14 ----
> 3 files changed, 164 insertions(+), 44 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> index f9749924a055..e5d67e01409c 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> @@ -205,52 +231,75 @@ const struct coresight_ops tmc_etf_cs_ops = {
>
> int tmc_read_prepare_etf(struct tmc_drvdata *drvdata)
> {
> - int ret = 0;
> enum tmc_mode mode;
> unsigned long flags;
>
> spin_lock_irqsave(&drvdata->spinlock, flags);
>
> - /* The TMC isn't enable, so there is no need to disable it */
> - if (!drvdata->enable)
> + /* The TMC isn't enabled, so there is no need to disable it */
> + if (!drvdata->enable) {
> + /*
> + * The ETB/ETF is disabled already. If drvdata::buf is NULL
> + * trace data has been harvested.
> + */
> + if (!drvdata->buf) {
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> + return -EINVAL;
> + }
> +
> goto out;
> + }
>
> if (drvdata->config_type != TMC_CONFIG_TYPE_ETB &&
> drvdata->config_type != TMC_CONFIG_TYPE_ETF) {
> - ret = -EINVAL;
> - goto out;
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> + return -EINVAL;
> }
>
> /* There is no point in reading a TMC in HW FIFO mode */
> mode = readl_relaxed(drvdata->base + TMC_MODE);
> if (mode != TMC_MODE_CIRCULAR_BUFFER) {
> - ret = -EINVAL;
> - goto out;
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> + return -EINVAL;
> }
>
> tmc_etb_disable_hw(drvdata);
> - drvdata->reading = true;
> + tmc_etb_dump_hw(drvdata);
The addition of tmc_etb_dump_hw() should have been part of the previous patch,
which made disable() reusable.
>
> out:
> + drvdata->reading = true;
Instead of spilling the spin_unlock_irq_restore() and return from too many
different places in the function above, could we do :
done:
drvdata->reading = true;
out:
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
> - return ret;
> + return 0;
> }
>
> int tmc_read_unprepare_etf(struct tmc_drvdata *drvdata)
> {
...
> + }
> +
> + /* The TMC isn't enabled, so there is no need to enable it */
> + if (!drvdata->enable) {
> + /*
> + * The ETB/ETF is not tracing and the buffer was just read.
> + * As such prepare to free the trace buffer.
> + */
> + buf = drvdata->buf;
> +
> + /*
> + * drvdata::buf is switched on in tmc_read_prepare_etf() so
> + * it is important to set it back to NULL.
> + */
> + drvdata->buf = NULL;
> goto out;
> }
This check should be brought down after the MODE check below for better error
check.
>
> @@ -258,13 +307,25 @@ int tmc_read_unprepare_etf(struct tmc_drvdata *drvdata)
> mode = readl_relaxed(drvdata->base + TMC_MODE);
> if (mode != TMC_MODE_CIRCULAR_BUFFER) {
> ret = -EINVAL;
> - goto out;
> + goto err;
> }
>
> + /*
> + * The trace run will continue with the same allocated trace buffer.
> + * As such zero-out the buffer so that we don't end up with stale
> + * data.
> + */
Could this drvdata->buf be NULL here ?
> + memset(drvdata->buf, 0, drvdata->size);
> tmc_etb_enable_hw(drvdata);
> - drvdata->reading = false;
>
> out:
> + drvdata->reading = false;
> +
> +err:
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
> +
> + /* Free allocated memory outside of the spinlock */
> + kfree(buf);
> +
> return ret;
> }
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 67e7d5dd891f..c4962568276e 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -16,6 +16,8 @@
> */
>
> #include <linux/coresight.h>
> +#include <linux/dma-mapping.h>
> +
> #include "coresight-priv.h"
> #include "coresight-tmc.h"
>
> @@ -82,19 +84,51 @@ static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata)
>
> static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode)
> {
> + bool allocated = false;
> unsigned long flags;
> + void __iomem *vaddr;
> + dma_addr_t paddr;
> struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>
> + /*
> + * 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;
> +
> spin_lock_irqsave(&drvdata->spinlock, flags);
> if (drvdata->reading) {
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
> + dma_free_coherent(drvdata->dev, drvdata->size, vaddr, paddr);
> return -EBUSY;
> }
Both here and above in the etf/etb case, could we do a preliminary check
by taking the lock where we may not have to allocate the buffer and allocate
it if necessary and retake the lock ? I know it could make the code a bit more
complex, but could save us on unnecessary allocations.
Also it would be good to consolidate the return points here as well for the
error path.
>
> + /*
> + * If drvdata::buf == NULL, use the memory allocated above.
> + * Otherwise a buffer still exists from a previous session, so
> + * simply use that.
> + */
> + if (!drvdata->buf) {
> + allocated = true;
> + drvdata->vaddr = vaddr;
> + drvdata->paddr = paddr;
> + drvdata->buf = drvdata->vaddr;
> + }
> +
> + memset(drvdata->vaddr, 0, drvdata->size);
> +
> tmc_etr_enable_hw(drvdata);
> drvdata->enable = true;
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>
> + /* Free memory outside the spinlock if need be */
> + if (!allocated)
> + dma_free_coherent(drvdata->dev, drvdata->size, vaddr, paddr);
> +
> dev_info(drvdata->dev, "TMC-ETR enabled\n");
> return 0;
> }
> @@ -129,48 +163,87 @@ const struct coresight_ops tmc_etr_cs_ops = {
>
> int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
> {
> - int ret = 0;
> unsigned long flags;
>
> spin_lock_irqsave(&drvdata->spinlock, flags);
>
> - /* The TMC isn't enable, so there is no need to disable it */
> - if (!drvdata->enable)
> + /* The TMC isn't enabled, so there is no need to disable it */
> + if (!drvdata->enable) {
> + /*
> + * The ETR is disabled already. If drvdata::buf is NULL
> + * trace data has been harvested.
> + */
> + if (!drvdata->buf) {
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> + return -EINVAL;
> + }
> +
> goto out;
> + }
>
> if (drvdata->config_type != TMC_CONFIG_TYPE_ETR) {
> - ret = -EINVAL;
> - goto out;
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> + return -EINVAL;
> }
>
> tmc_etr_disable_hw(drvdata);
> - drvdata->reading = true;
> + tmc_etr_dump_hw(drvdata);
Same as for etf/etb, shouldn't the above dump_hw be part of the previous patch ?
>
> out:
> + drvdata->reading = true;
> spin_unlock_irqrestore(&drvdata->spinlock, flags);
> - return ret;
> + return 0;
> }
>
> int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
> {
> int ret = 0;
> unsigned long flags;
> + void __iomem *vaddr = NULL;
> + dma_addr_t paddr;
>
> spin_lock_irqsave(&drvdata->spinlock, flags);
>
> - /* The TMC isn't enable, so there is no need to enable it */
> - if (!drvdata->enable)
> - goto out;
> -
> if (drvdata->config_type != TMC_CONFIG_TYPE_ETR) {
> ret = -EINVAL;
> + goto err;
> + }
> +
> + /* The TMC isn't enabled, so there is no need to enable it */
> + if (!drvdata->enable) {
> + /*
> + * The ETR is not tracing and trace data was just read. As
> + * such prepare to free the trace buffer.
> + */
> + vaddr = drvdata->vaddr;
> + paddr = drvdata->paddr;
> +
> + /*
> + * drvdata::buf is switched on in tmc_read_prepare_etr() and
> + * tmc_enable_etr_sink so it is important to set it back to
> + * NULL.
> + */
> + drvdata->buf = NULL;
> goto out;
> }
>
> + /*
> + * The trace run will continue with the same allocated trace buffer.
> + * As such zero-out the buffer so that we don't end up with stale
> + * data.
> + */
> + memset(drvdata->buf, 0, drvdata->size);
Are we sure drvdata->buf is not NULL here ?
Suzuki
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| From | Mathieu Poirier <mathieu.poirier@linaro.org> |
|---|---|
| Date | 2016-04-08 17:30 +0200 |
| Message-ID | <rlGwa-5UD-15@gated-at.bofh.it> |
| In reply to | #1373570 |
On 7 April 2016 at 10:50, Suzuki K Poulose <Suzuki.Poulose@arm.com> wrote:
> On 22/03/16 20:23, Mathieu Poirier wrote:
>>
>> In it's current form the TMC probe() function allocates
>> trace buffer memory at boot time, event if coresight isn't
>> used. This is highly inefficient since trace buffers can
>> occupy a lot of memory that could be used otherwised.
>>
>> This patch allocates trace buffers on the fly, when the
>> coresight subsytem is sollicited. Allocated buffers are
>
>
> nit: *subsystem* is *solicited*.
Ack
>
>> released when traces are read using the device descriptors
>> under /dev.
>>
>> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
>> ---
>> drivers/hwtracing/coresight/coresight-tmc-etf.c | 97
>> ++++++++++++++++++++-----
>> drivers/hwtracing/coresight/coresight-tmc-etr.c | 97
>> ++++++++++++++++++++++---
>> drivers/hwtracing/coresight/coresight-tmc.c | 14 ----
>> 3 files changed, 164 insertions(+), 44 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c
>> b/drivers/hwtracing/coresight/coresight-tmc-etf.c
>> index f9749924a055..e5d67e01409c 100644
>> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
>> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
>
>
>
>> @@ -205,52 +231,75 @@ const struct coresight_ops tmc_etf_cs_ops = {
>>
>> int tmc_read_prepare_etf(struct tmc_drvdata *drvdata)
>> {
>> - int ret = 0;
>> enum tmc_mode mode;
>> unsigned long flags;
>>
>> spin_lock_irqsave(&drvdata->spinlock, flags);
>>
>> - /* The TMC isn't enable, so there is no need to disable it */
>> - if (!drvdata->enable)
>> + /* The TMC isn't enabled, so there is no need to disable it */
>> + if (!drvdata->enable) {
>> + /*
>> + * The ETB/ETF is disabled already. If drvdata::buf is
>> NULL
>> + * trace data has been harvested.
>> + */
>> + if (!drvdata->buf) {
>> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
>> + return -EINVAL;
>> + }
>> +
>> goto out;
>> + }
>>
>> if (drvdata->config_type != TMC_CONFIG_TYPE_ETB &&
>> drvdata->config_type != TMC_CONFIG_TYPE_ETF) {
>> - ret = -EINVAL;
>> - goto out;
>> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
>> + return -EINVAL;
>> }
>>
>> /* There is no point in reading a TMC in HW FIFO mode */
>> mode = readl_relaxed(drvdata->base + TMC_MODE);
>> if (mode != TMC_MODE_CIRCULAR_BUFFER) {
>> - ret = -EINVAL;
>> - goto out;
>> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
>> + return -EINVAL;
>> }
>
>
>>
>> tmc_etb_disable_hw(drvdata);
>> - drvdata->reading = true;
>> + tmc_etb_dump_hw(drvdata);
>
>
> The addition of tmc_etb_dump_hw() should have been part of the previous
> patch,
> which made disable() reusable.
Thanks for your comment on this patchset.
After Dan found an error with the memory allocation I started to look
at the driver again and found several areas worth improving. I'm
currently re-writing this patchset and the result should be much
easier to follow. I would appreciate if you can have a look when V2
is out.
Best regards,
Mathieu
[1]. http://www.spinics.net/lists/arm-kernel/msg494888.html
>
>>
>> out:
>> + drvdata->reading = true;
>
>
> Instead of spilling the spin_unlock_irq_restore() and return from too many
> different places in the function above, could we do :
>
> done:
> drvdata->reading = true;
>
> out:
>>
>> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>> - return ret;
>> + return 0;
>
>
>
>> }
>>
>> int tmc_read_unprepare_etf(struct tmc_drvdata *drvdata)
>> {
>
>
> ...
>
>> + }
>> +
>> + /* The TMC isn't enabled, so there is no need to enable it */
>> + if (!drvdata->enable) {
>> + /*
>> + * The ETB/ETF is not tracing and the buffer was just
>> read.
>> + * As such prepare to free the trace buffer.
>> + */
>> + buf = drvdata->buf;
>> +
>> + /*
>> + * drvdata::buf is switched on in tmc_read_prepare_etf()
>> so
>> + * it is important to set it back to NULL.
>> + */
>> + drvdata->buf = NULL;
>> goto out;
>> }
>
>
> This check should be brought down after the MODE check below for better
> error
> check.
>
>>
>> @@ -258,13 +307,25 @@ int tmc_read_unprepare_etf(struct tmc_drvdata
>> *drvdata)
>> mode = readl_relaxed(drvdata->base + TMC_MODE);
>> if (mode != TMC_MODE_CIRCULAR_BUFFER) {
>> ret = -EINVAL;
>> - goto out;
>> + goto err;
>> }
>>
>> + /*
>> + * The trace run will continue with the same allocated trace
>> buffer.
>> + * As such zero-out the buffer so that we don't end up with stale
>> + * data.
>> + */
>
>
> Could this drvdata->buf be NULL here ?
>
>> + memset(drvdata->buf, 0, drvdata->size);
>> tmc_etb_enable_hw(drvdata);
>> - drvdata->reading = false;
>>
>> out:
>> + drvdata->reading = false;
>> +
>> +err:
>> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>> +
>> + /* Free allocated memory outside of the spinlock */
>> + kfree(buf);
>> +
>> return ret;
>> }
>> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c
>> b/drivers/hwtracing/coresight/coresight-tmc-etr.c
>> index 67e7d5dd891f..c4962568276e 100644
>> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
>> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
>> @@ -16,6 +16,8 @@
>> */
>>
>> #include <linux/coresight.h>
>> +#include <linux/dma-mapping.h>
>> +
>> #include "coresight-priv.h"
>> #include "coresight-tmc.h"
>>
>> @@ -82,19 +84,51 @@ static void tmc_etr_disable_hw(struct tmc_drvdata
>> *drvdata)
>>
>> static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode)
>> {
>> + bool allocated = false;
>> unsigned long flags;
>> + void __iomem *vaddr;
>> + dma_addr_t paddr;
>> struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
>>
>> + /*
>> + * 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;
>> +
>> spin_lock_irqsave(&drvdata->spinlock, flags);
>> if (drvdata->reading) {
>> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>> + dma_free_coherent(drvdata->dev, drvdata->size, vaddr,
>> paddr);
>> return -EBUSY;
>> }
>
>
> Both here and above in the etf/etb case, could we do a preliminary check
> by taking the lock where we may not have to allocate the buffer and allocate
> it if necessary and retake the lock ? I know it could make the code a bit
> more
> complex, but could save us on unnecessary allocations.
>
> Also it would be good to consolidate the return points here as well for the
> error path.
>
>>
>> + /*
>> + * If drvdata::buf == NULL, use the memory allocated above.
>> + * Otherwise a buffer still exists from a previous session, so
>> + * simply use that.
>> + */
>> + if (!drvdata->buf) {
>> + allocated = true;
>> + drvdata->vaddr = vaddr;
>> + drvdata->paddr = paddr;
>> + drvdata->buf = drvdata->vaddr;
>> + }
>> +
>> + memset(drvdata->vaddr, 0, drvdata->size);
>> +
>> tmc_etr_enable_hw(drvdata);
>> drvdata->enable = true;
>> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>>
>> + /* Free memory outside the spinlock if need be */
>> + if (!allocated)
>> + dma_free_coherent(drvdata->dev, drvdata->size, vaddr,
>> paddr);
>> +
>> dev_info(drvdata->dev, "TMC-ETR enabled\n");
>> return 0;
>> }
>> @@ -129,48 +163,87 @@ const struct coresight_ops tmc_etr_cs_ops = {
>>
>> int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
>> {
>> - int ret = 0;
>> unsigned long flags;
>>
>> spin_lock_irqsave(&drvdata->spinlock, flags);
>>
>> - /* The TMC isn't enable, so there is no need to disable it */
>> - if (!drvdata->enable)
>> + /* The TMC isn't enabled, so there is no need to disable it */
>> + if (!drvdata->enable) {
>> + /*
>> + * The ETR is disabled already. If drvdata::buf is NULL
>> + * trace data has been harvested.
>> + */
>> + if (!drvdata->buf) {
>> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
>> + return -EINVAL;
>> + }
>> +
>> goto out;
>> + }
>>
>> if (drvdata->config_type != TMC_CONFIG_TYPE_ETR) {
>> - ret = -EINVAL;
>> - goto out;
>> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
>> + return -EINVAL;
>> }
>>
>> tmc_etr_disable_hw(drvdata);
>> - drvdata->reading = true;
>> + tmc_etr_dump_hw(drvdata);
>
>
> Same as for etf/etb, shouldn't the above dump_hw be part of the previous
> patch ?
>
>>
>> out:
>> + drvdata->reading = true;
>> spin_unlock_irqrestore(&drvdata->spinlock, flags);
>> - return ret;
>> + return 0;
>> }
>>
>> int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
>> {
>> int ret = 0;
>> unsigned long flags;
>> + void __iomem *vaddr = NULL;
>> + dma_addr_t paddr;
>>
>> spin_lock_irqsave(&drvdata->spinlock, flags);
>>
>> - /* The TMC isn't enable, so there is no need to enable it */
>> - if (!drvdata->enable)
>> - goto out;
>> -
>> if (drvdata->config_type != TMC_CONFIG_TYPE_ETR) {
>> ret = -EINVAL;
>> + goto err;
>> + }
>> +
>> + /* The TMC isn't enabled, so there is no need to enable it */
>> + if (!drvdata->enable) {
>> + /*
>> + * The ETR is not tracing and trace data was just read. As
>> + * such prepare to free the trace buffer.
>> + */
>> + vaddr = drvdata->vaddr;
>> + paddr = drvdata->paddr;
>> +
>> + /*
>> + * drvdata::buf is switched on in tmc_read_prepare_etr()
>> and
>> + * tmc_enable_etr_sink so it is important to set it back
>> to
>> + * NULL.
>> + */
>> + drvdata->buf = NULL;
>> goto out;
>> }
>>
>> + /*
>> + * The trace run will continue with the same allocated trace
>> buffer.
>> + * As such zero-out the buffer so that we don't end up with stale
>> + * data.
>> + */
>> + memset(drvdata->buf, 0, drvdata->size);
>
>
> Are we sure drvdata->buf is not NULL here ?
>
>
> Suzuki
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