| Message ID | 20230922093842.2646157-2-haowenchao2@huawei.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | cleanup patch | expand |
On 2023/09/22 2:38, Wenchao Hao wrote: > This is just a cleanup for scsi_dev_queue_ready() to avoid > redundant goto and if statement, it did not change the origin > logic. > > Signed-off-by: Wenchao Hao <haowenchao2@huawei.com> > --- > drivers/scsi/scsi_lib.c | 35 ++++++++++++++++++----------------- > 1 file changed, 18 insertions(+), 17 deletions(-) > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index ca5eb058d5c7..f3e388127dbd 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1254,28 +1254,29 @@ static inline int scsi_dev_queue_ready(struct request_queue *q, > int token; > > token = sbitmap_get(&sdev->budget_map); > - if (atomic_read(&sdev->device_blocked)) { > - if (token < 0) > - goto out; > + if (token < 0) > + return -1; This is changing how this function works... > > - if (scsi_device_busy(sdev) > 1) > - goto out_dec; > + /* > + * device_blocked is not set at mostly time, so check it first > + * and return token when it is not set. > + */ > + if (!atomic_read(&sdev->device_blocked)) > + return token; ...because you reversed the tests order. > > - /* > - * unblock after device_blocked iterates to zero > - */ > - if (atomic_dec_return(&sdev->device_blocked) > 0) > - goto out_dec; > - SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, > - "unblocking device at zero depth\n")); > + /* > + * unblock after device_blocked iterates to zero > + */ > + if (scsi_device_busy(sdev) > 1 || > + atomic_dec_return(&sdev->device_blocked) > 0) { And here too, you are changing how the function works. The atomic_dec may not be done if the first condition is true. > + sbitmap_put(&sdev->budget_map, token); > + return -1; > } > > + SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, > + "unblocking device at zero depth\n")); > + > return token; > -out_dec: > - if (token >= 0) > - sbitmap_put(&sdev->budget_map, token); > -out: > - return -1; > } > > /*
On 2023/9/22 20:50, Damien Le Moal wrote: > On 2023/09/22 2:38, Wenchao Hao wrote: >> This is just a cleanup for scsi_dev_queue_ready() to avoid >> redundant goto and if statement, it did not change the origin >> logic. >> >> Signed-off-by: Wenchao Hao <haowenchao2@huawei.com> >> --- >> drivers/scsi/scsi_lib.c | 35 ++++++++++++++++++----------------- >> 1 file changed, 18 insertions(+), 17 deletions(-) >> >> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c >> index ca5eb058d5c7..f3e388127dbd 100644 >> --- a/drivers/scsi/scsi_lib.c >> +++ b/drivers/scsi/scsi_lib.c >> @@ -1254,28 +1254,29 @@ static inline int scsi_dev_queue_ready(struct request_queue *q, >> int token; >> >> token = sbitmap_get(&sdev->budget_map); >> - if (atomic_read(&sdev->device_blocked)) { >> - if (token < 0) >> - goto out; >> + if (token < 0) >> + return -1; > > This is changing how this function works... > I don't think so... The origin function flow: static inline int scsi_dev_queue_ready(struct request_queue *q, struct scsi_device *sdev) { ... token = sbitmap_get(&sdev->budget_map); if (atomic_read(&sdev->device_blocked)) { if (token < 0) goto out; } return token; out: return -1 } If the token is less than 0, it would always return -1. So we can found it's not necessary to check token after atomic_read(). >> >> - if (scsi_device_busy(sdev) > 1) >> - goto out_dec; >> + /* >> + * device_blocked is not set at mostly time, so check it first >> + * and return token when it is not set. >> + */ >> + if (!atomic_read(&sdev->device_blocked)) >> + return token; > > ...because you reversed the tests order. As explained in comment, the device_blocked is not set at mostly time, so when it's not set, just return the token. >> >> - /* >> - * unblock after device_blocked iterates to zero >> - */ >> - if (atomic_dec_return(&sdev->device_blocked) > 0) >> - goto out_dec; >> - SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, >> - "unblocking device at zero depth\n")); >> + /* >> + * unblock after device_blocked iterates to zero >> + */ >> + if (scsi_device_busy(sdev) > 1 || >> + atomic_dec_return(&sdev->device_blocked) > 0) { > > And here too, you are changing how the function works. The atomic_dec may not be > done if the first condition is true. > the origin flow would not call atomic_dec_return() too when condition "scsi_device_busy(sdev) > 1" is true like following: static inline int scsi_dev_queue_ready(struct request_queue *q, struct scsi_device *sdev) { ... if (atomic_read(&sdev->device_blocked)) { if (scsi_device_busy(sdev) > 1) goto out_dec; /* * unblock after device_blocked iterates to zero */ if (atomic_dec_return(&sdev->device_blocked) > 0) goto out_dec; SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, "unblocking device at zero depth\n")); } return token; out_dec: if (token >= 0) sbitmap_put(&sdev->budget_map, token); out: return -1; } Here is the function before and after my change: The old function: static inline int scsi_dev_queue_ready(struct request_queue *q, struct scsi_device *sdev) { int token; token = sbitmap_get(&sdev->budget_map); if (token < 0) return -1; /* * device_blocked is not set at mostly time, so check it first * and return token when it is not set. */ if (!atomic_read(&sdev->device_blocked)) return token; /* * unblock after device_blocked iterates to zero */ if (scsi_device_busy(sdev) > 1 || atomic_dec_return(&sdev->device_blocked) > 0) { sbitmap_put(&sdev->budget_map, token); return -1; } SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, "unblocking device at zero depth\n")); return token; } Function after my change: static inline int scsi_dev_queue_ready(struct request_queue *q, struct scsi_device *sdev) { int token; token = sbitmap_get(&sdev->budget_map); if (token < 0) return -1; /* * device_blocked is not set at mostly time, so check it first * and return token when it is not set. */ if (!atomic_read(&sdev->device_blocked)) return token; /* * unblock after device_blocked iterates to zero */ if (scsi_device_busy(sdev) > 1 || atomic_dec_return(&sdev->device_blocked) > 0) { sbitmap_put(&sdev->budget_map, token); return -1; } SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, "unblocking device at zero depth\n")); return token; } I think it looks more clear and readable than before. >> + sbitmap_put(&sdev->budget_map, token); >> + return -1; >> } >> >> + SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, >> + "unblocking device at zero depth\n")); >> + >> return token; >> -out_dec: >> - if (token >= 0) >> - sbitmap_put(&sdev->budget_map, token); >> -out: >> - return -1; >> } >> >> /* >
On 2023/9/24 14:27, Wenchao Hao wrote: > On 2023/9/22 20:50, Damien Le Moal wrote: >> On 2023/09/22 2:38, Wenchao Hao wrote: >>> This is just a cleanup for scsi_dev_queue_ready() to avoid >>> redundant goto and if statement, it did not change the origin >>> logic. >>> >>> Signed-off-by: Wenchao Hao <haowenchao2@huawei.com> >>> --- >>> drivers/scsi/scsi_lib.c | 35 ++++++++++++++++++----------------- >>> 1 file changed, 18 insertions(+), 17 deletions(-) >>> >>> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c >>> index ca5eb058d5c7..f3e388127dbd 100644 >>> --- a/drivers/scsi/scsi_lib.c >>> +++ b/drivers/scsi/scsi_lib.c >>> @@ -1254,28 +1254,29 @@ static inline int scsi_dev_queue_ready(struct request_queue *q, >>> int token; >>> token = sbitmap_get(&sdev->budget_map); >>> - if (atomic_read(&sdev->device_blocked)) { >>> - if (token < 0) >>> - goto out; >>> + if (token < 0) >>> + return -1; >> >> This is changing how this function works... >> > > I don't think so... > The origin function flow: > > static inline int scsi_dev_queue_ready(struct request_queue *q, > struct scsi_device *sdev) > { > ... > token = sbitmap_get(&sdev->budget_map); > if (atomic_read(&sdev->device_blocked)) { > if (token < 0) > goto out; > } > return token; > out: > return -1 > } > > If the token is less than 0, it would always return -1. So we can found > it's not necessary to check token after atomic_read(). > >>> - if (scsi_device_busy(sdev) > 1) >>> - goto out_dec; >>> + /* >>> + * device_blocked is not set at mostly time, so check it first >>> + * and return token when it is not set. >>> + */ >>> + if (!atomic_read(&sdev->device_blocked)) >>> + return token; >> >> ...because you reversed the tests order. > > As explained in comment, the device_blocked is not set at mostly time, > so when it's not set, just return the token. > >>> - /* >>> - * unblock after device_blocked iterates to zero >>> - */ >>> - if (atomic_dec_return(&sdev->device_blocked) > 0) >>> - goto out_dec; >>> - SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, >>> - "unblocking device at zero depth\n")); >>> + /* >>> + * unblock after device_blocked iterates to zero >>> + */ >>> + if (scsi_device_busy(sdev) > 1 || >>> + atomic_dec_return(&sdev->device_blocked) > 0) { >> >> And here too, you are changing how the function works. The atomic_dec may not be >> done if the first condition is true. >> > > the origin flow would not call atomic_dec_return() too when condition > "scsi_device_busy(sdev) > 1" is true like following: > > static inline int scsi_dev_queue_ready(struct request_queue *q, > struct scsi_device *sdev) > { > ... > if (atomic_read(&sdev->device_blocked)) { > if (scsi_device_busy(sdev) > 1) > goto out_dec; > > /* > * unblock after device_blocked iterates to zero > */ > if (atomic_dec_return(&sdev->device_blocked) > 0) > goto out_dec; > SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, > "unblocking device at zero depth\n")); > } > return token; > out_dec: > if (token >= 0) > sbitmap_put(&sdev->budget_map, token); > out: > return -1; > } > > Here is the function before and after my change: > > The old function: > static inline int scsi_dev_queue_ready(struct request_queue *q, > struct scsi_device *sdev) > { > int token; > > token = sbitmap_get(&sdev->budget_map); > if (token < 0) > return -1; > > /* > * device_blocked is not set at mostly time, so check it first > * and return token when it is not set. > */ > if (!atomic_read(&sdev->device_blocked)) > return token; > > /* > * unblock after device_blocked iterates to zero > */ > if (scsi_device_busy(sdev) > 1 || > atomic_dec_return(&sdev->device_blocked) > 0) { > sbitmap_put(&sdev->budget_map, token); > return -1; > } > > SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, > "unblocking device at zero depth\n")); > > return token; > } > Sorry, I paste wrong for old function, the old function is: static inline int scsi_dev_queue_ready(struct request_queue *q, struct scsi_device *sdev) { int token; token = sbitmap_get(&sdev->budget_map); if (atomic_read(&sdev->device_blocked)) { if (token < 0) goto out; if (scsi_device_busy(sdev) > 1) goto out_dec; /* * unblock after device_blocked iterates to zero */ if (atomic_dec_return(&sdev->device_blocked) > 0) goto out_dec; SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, "unblocking device at zero depth\n")); } return token; out_dec: if (token >= 0) sbitmap_put(&sdev->budget_map, token); out: return -1; }
On 2023/9/24 14:27, Wenchao Hao wrote: > On 2023/9/22 20:50, Damien Le Moal wrote: >> On 2023/09/22 2:38, Wenchao Hao wrote: >>> This is just a cleanup for scsi_dev_queue_ready() to avoid >>> redundant goto and if statement, it did not change the origin >>> logic. >>> >>> Signed-off-by: Wenchao Hao <haowenchao2@huawei.com> >>> --- >>> drivers/scsi/scsi_lib.c | 35 ++++++++++++++++++----------------- >>> 1 file changed, 18 insertions(+), 17 deletions(-) >>> >>> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c >>> index ca5eb058d5c7..f3e388127dbd 100644 >>> --- a/drivers/scsi/scsi_lib.c >>> +++ b/drivers/scsi/scsi_lib.c >>> @@ -1254,28 +1254,29 @@ static inline int scsi_dev_queue_ready(struct request_queue *q, >>> int token; >>> token = sbitmap_get(&sdev->budget_map); >>> - if (atomic_read(&sdev->device_blocked)) { >>> - if (token < 0) >>> - goto out; >>> + if (token < 0) >>> + return -1; >> >> This is changing how this function works... >> > > I don't think so... > The origin function flow: > > static inline int scsi_dev_queue_ready(struct request_queue *q, > struct scsi_device *sdev) > { > ... > token = sbitmap_get(&sdev->budget_map); > if (atomic_read(&sdev->device_blocked)) { > if (token < 0) > goto out; > } > return token; > out: > return -1 > } > > If the token is less than 0, it would always return -1. So we can found > it's not necessary to check token after atomic_read(). > >>> - if (scsi_device_busy(sdev) > 1) >>> - goto out_dec; >>> + /* >>> + * device_blocked is not set at mostly time, so check it first >>> + * and return token when it is not set. >>> + */ >>> + if (!atomic_read(&sdev->device_blocked)) >>> + return token; >> >> ...because you reversed the tests order. > > As explained in comment, the device_blocked is not set at mostly time, > so when it's not set, just return the token. > Friendly ping...
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index ca5eb058d5c7..f3e388127dbd 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1254,28 +1254,29 @@ static inline int scsi_dev_queue_ready(struct request_queue *q, int token; token = sbitmap_get(&sdev->budget_map); - if (atomic_read(&sdev->device_blocked)) { - if (token < 0) - goto out; + if (token < 0) + return -1; - if (scsi_device_busy(sdev) > 1) - goto out_dec; + /* + * device_blocked is not set at mostly time, so check it first + * and return token when it is not set. + */ + if (!atomic_read(&sdev->device_blocked)) + return token; - /* - * unblock after device_blocked iterates to zero - */ - if (atomic_dec_return(&sdev->device_blocked) > 0) - goto out_dec; - SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, - "unblocking device at zero depth\n")); + /* + * unblock after device_blocked iterates to zero + */ + if (scsi_device_busy(sdev) > 1 || + atomic_dec_return(&sdev->device_blocked) > 0) { + sbitmap_put(&sdev->budget_map, token); + return -1; } + SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, + "unblocking device at zero depth\n")); + return token; -out_dec: - if (token >= 0) - sbitmap_put(&sdev->budget_map, token); -out: - return -1; } /*
This is just a cleanup for scsi_dev_queue_ready() to avoid redundant goto and if statement, it did not change the origin logic. Signed-off-by: Wenchao Hao <haowenchao2@huawei.com> --- drivers/scsi/scsi_lib.c | 35 ++++++++++++++++++----------------- 1 file changed, 18 insertions(+), 17 deletions(-)